U.S. DEPARTMENT OF COMMERCE
National Technical Information Service
PB-288 892
The Transfer Function of Quarry Blast
Noise and Vibration into Typical
Residential Structures
Kamperman Associates, Inc, Downers Grove, IL
Prepared for
Environmental Protection Agency, Washington, DC Office of Noise Abatement
and Control
Feb 77
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TECHNICAL REPORT DATA
Please read Instructions on the reverse before complennel
1 REPORT NO 2.
EPA 550/9-77-351
PB 288892 J
4. TITLE AND SUBTITLE
The Transfer Function of Quarry Blast Noise and
Vibration into Typical Residential Structures
February 1977
6. PERFORMING ORGANIZATION CODE j
7 AUTHOR(S)
George W. .Kamperman and Mary A. Nicholson
8. PERFORMING ORGANIZATION REPORT NO. j
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Kamperman Associates, Inc.
1110 Hickory Trail
Downers Grove, Illinois 60515
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-01-4134
12. SPONSORING AGENCY NAME AND ADDRESS
Environmental Protection Agency
Office of Noise Abatement and Control
Washington, D.C. 20460
13. TYPE OF REPORT AND PERIOD COVERED I
Final
14. SPONSORING AGENCY CODE I
AW-471
15. SUPPLEMENTARY NOTES j
16. ABSTRACT
An experimental program was conducted to determine the transfer function of quarry
blast noise and vibration into typical structures. Four distinct noise and vibration
signals are produced inside nearby dwellings. It was determined that due to resonances
excited within the dwel1ings,the noise and vibration excitation was greater inside
the dwellings than outside.
' REPRODUCED BY
NATIONAL TECHNICAL
INFORMATION SERVICE
U. S. DEPARTMENT OF COMMERCE
SPRINGFIELD. VA. 22161
17. KEY WORDS AND DOCUMENT ANALYSIS
a. - DESCRIPTORS
b.JDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Noise, Blast Noise, Blast Noise Transfer
Function, House Noise, Quarry Blast,
Vibrations, Residential Structures, Outdoor
Measurements, Indoor Measurements
18. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (This Report)
Unclassified
21. NO. C
20 SECURITY CLASS (This page)
Unclassified
fC OO 7
/Dp- &0 ( (
EPA Form 2220-1 (9-73)
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THE TRANSFER FUNCTION OF
QUARRY BLAST NOISE AND VIBRATION
INTO TYPICAL RESIDENTIAL STRUCTURES
February 1977
Prepared by
KAMPERMAN ASSOCIATES, INC.
under
CONTRACT 68-01-4134
for the
U.S. Environmental Protection Agency
Office of Noise Abatement and Control
Washington, D.C. 20460
This report has been approved for general availability.
The contents of this report reflect the views of the
contractor, who is responsible for the facts and the
accuracy of the data presented herein, and do not necessarily
reflect the official views or policy of EPA. This report
does not constitute a standard, specification, or regulation.
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TABLE OF CONTENTS
Page
1.0 INTRODUCTION 1
1.1 Current Information Available on Quarry
Blast Noise and Vibration 1
1.2 Purpose of This Research Study 3
2.0 SUMMARY 4
2.1 Blast Noise and Vibration Descriptors 4
2.2 Blast Noise and Vibration Measurement
Methodologies 6
2.3 Data Reduction Methodologies 8
2.4 Selection of Descriptors of Human
Annoyance 8
2.5 Determining the Transfer Function for Blast
Noise and Vibration from Outside to Inside
Typical Dwellings 9
2.6 Relating the Magnitude of Blast Noise and
Vibration to Quarry Blasting Techniques 9
3.0 CONCLUSIONS AND RESULTS OF STUDY '10
3.1 Frequency Range of Interest 10
3.2 Amplitude Measures of Blast Noise and Vibration 11
3.3 Human Annoyance Descriptors Applied Inside a
Dwelling 12
3.4 The Rank Ordering of Outdoor Blast Noise and
Vibration Descriptors that Correlate Best with
the Indoor Human Annoyance Descriptors 14
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Page
3.5 Comparison of Outdoor Air Blast Descriptors 21
3.6 The Importance of the One Hertz Air Blast Peak 23
3.7 Predicting the Amplitude of Quarry Blast Noise
and Vibration 2 5
3.8 General Observations 33
4.0 RECOMMENDATIONS 34
4.1 Suggestions for Monitoring Blasting Events with
Respect to Annoyance of Residents in Typical
Dwellings 3 5
4.2 Future Research Needed to Formulate a Blast Noise
and Vibration Regulation 36
4.2.1 Psychological Studies for Long Duration
Impulses 36
4.2.2 Effects on Various Blasting Configurations 37
4.2.3 Economic Impact Versus Blast Noise and
Vibration Control 41
4.2.4 Determine the Transfer Function for a
Broader Range of Living Quarters 41
REFERENCES 42
APPENDIX A. DETAILS OF QUARRY BLAST NOISE STUDY A-l
A.1 Measurement Objectives A-l
A.1.1 Blast Noise and Vibration Parameters
to be Measured and Studied A-2
A. 1.2 Frequency Range of Interest A-3
A.1.3 Dynamic Signal Range of Interest A-4
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LIST OF TABLES
Table
Number Page
2.1-1 Blast Noise Descriptors 4
2.1-2 Vibration Descriptors 5
3.4-1 Rank ordering (by standard deviation) of
outdoor measurement of ground velocity minus
indoor measurement of floor velocity. 15
3.4-2 Rank ordering (by standard deviation) of
measurements of outdoor ground velocity level
minus indoor sound pressure level. 17
3.4-3 Rank ordering (by standard deviation) of
measurements of outdoor sound pressure level
minus indoor sound pressure level. 19
3.4-4 Rank ordering (by standard deviation) of
measurements of outdoor sound pressure level
minus indoor floor velocity level. 20
3.5-1 Comparison of outdoor air blast descriptors
(descriptor A minus descriptor B). 22
3.6-1 Integrated energy of vertical floor accelera-
tion according to ISO recommendations with
further frequency filtering. 24
A.4.3-1 Maximum instantaneous peaks of blast events
(except acceleration weighted through a
5.6 Hz low-pass filter from .5 Hz to 200 Hz). A-51
A.4.3-2 The SEL and VEL results of blast events
over a 4 Hz to 200 Hz filter (except
acceleration weighted through a 5.6 Hz low
pass filter from .5 Hz to 200 Hz). A-52
A.4.3-3 SEL of blast events through a C-weighting
network or an A-weighting network. A-53
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Page
A.1.4 Selection of Measuring Transducers A-4
A.1.5 Selection of Data-Recording Instruments A-9
A.1.6 Calibration of Instrumentation A-10
A. 1.7 Signal Cables and Connectors A-12
A.2 Blast Noise and Vibration Recording Systems A-13
A.2.1 The Mobile Recording System A-14
A.2.2 Portable Blast Noise Recorder A-19
A.2.3 Recording Systems Used in Illinois 1975
IEQ Blast Noise Study A-22
A.2.4 Alterations to the 1976 Mobile Recording
System A-23
A.3 Analysis of Recorded Blast Noise and Vibration A-26
A. 3.1 Data Analysis Systems A-26
A.3.2 Time History of Blast Event A-28
A.3.3 Spectrum Analysis and Frequency Weighting A-30
A.3.4 Determination of the Noise and Vibration
Energy (VEL) from a Blast Event A-35
A.4 Data Presentation and Interpretation A-39
A.4.1 Time History Records A-39
A.4.2 Frequency Spectra A-44
A.4.3 Single-Number Descriptors A-50
APPENDIX B. DETAILED TIME HISTORY OF 18 RECORDED STONE
QUARRY BLAST EVENTS BY KAMPERMAN ASSOCIATES INC.
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LIST OF FIGURES
Figure
Number Page
3.7-1 Velocity levels versus scaled distance. 26
3,7-2 Sound levels versus scaled distance. 28
3.7-3 Sound levels versus scaled distance for C-
weighted slow response. 31
3.7-4 Sound levels versus scaled distance. 32
4.2.2-1 Time history of blast prior to blowout. 39
4.2.2-2 Frequency spectrum of blast prior to hole
blowout. 39
4.2.2-3 Time history of blast, including hole
blowout (0.2 seconds total time elapsed). 40
4.2.2-4 Frequency spectrum of blast, including hole
blowout. 40
A.1.4-1 Blast noise and vibration-measurement
transducers.
A-7
A.1.5-1 Blast noise and vibration-recording instruments. A-10
A.1.5-2 Blast noise and vibration field recording
system used early in the measurement program. A-ll
A.2.2-1 Portable air blast recording system used by
Illinois EPA personnel for the 1975 IEQ and
1976 EPA quarry blast noise study. A-21
A.2.3-1 Blast noise recording and analysis system
used by Kamperman Associates Inc. for 1975
IEQ study. A-24
A.2.4-1 Blast noise and vibration field recording
system used for the major portion of the
measurement program. A-27
A. 3.1-1 Data analysis instrumentation. A-28
A.3.2-1 Simultaneous time history analysis of eight
noise and vibration signals recorded during
a single blast event. A-29
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Table
Number
Page
A. 4.3-4 Slow meter response of blast events through a
4 Hz to 200 Hz filter. A-54
A.4.3-5 Slow meter response of blast events through a
"C" weighting network. A-55
A.4.3-6 Outdoor sound pressure measurements of blast
events made by Illinois Environmental Protection
Agency in 1976 on quarry or coal mine property. A-56
A.4.3-7 Physical data on quarry blasts measured by
Kamperman Associates Inc. during August,
'September and October, 1976 A-59
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Figure
Number
Page
B-3
Oscillograph
record
of
blast
no. 3.
B-7
B-4
Oscillograph
record
of
blast
no. 4.
B-9
B-5
Oscillograph
record
of
blast
no. 5.
B-ll
B-6
Oscillograph
record
of
blast
no. 6.
B-13
B-7
Oscillograph
record
of
blast
no. 7.
B-15
B-8
Oscillograph
record
of
blast
no. 8.
B-17
B-9
Oscillograph
record
of
blast
no. 9.
B-19
B-10
Oscillograph
record
of
blast
no. 10.
B-21
B-ll
Oscillograph
record
of
blast
no. 11.
B-23
B-12
Oscillograph
record
of
blast
no. 12.
B-25
B-13
Oscillograph
record
of
blast
no. 13.
B-27
B-14
Oscillograph
record
of
blast
no. 14.
B-29
B-15
Oscillograph
record
of
blast
no. 15.
B-31
B-16
Osci1lograph
record
of
blast
no. 16.
B-33
B-17
Oscillograph
record
of
blast
no. 17.
B-35
B-18
Oscillograph
record
of
blast
no. 18.
B-37
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Figure
Number Page
A.3.3-1 Data analysis system for determining blast
noise and vibration spectrum peak and
various sound level meter descriptors. A-31
A.3.3-2 Amplitude—time history of an air blast. A-32
A. 3.3-3 Air blast frequency spectrum with rectangular
"window". A-32
A. 3.3-4 Air blast frequency spectrum with Hanning
"window". A-33
A.3.4-1 Data analysis system for determining blast
noise and vibration energy, SEL and VEL. A-36
A.4.1-1 Oscillograph record of blast no. 15. A-40
A.4.1-2 Oscillograph record of blast no. 7. A-42
A.4.2-1 Outdoor lateral ground velocity for blast no. 15. A-44
A.4.2-2 Outdoor vertical ground velocity for blast no.15. A-44
A.4.2-3 Outdoor sound pressure. A-45
A.4.2-4 Indoor lateral floor velocity due to the
ground wave. A-45
A.4.2-5 Indoor lateral floor velocity due to the air
wave. A-46
A.4.2-6 Indoor vertical floor velocity due to the
ground wave. A-46
A.4.2-7 Indoor vertical floor velocity due to the
air wave. A-47
A.4.2-8 Indoor vertical floor acceleration due to
the ground wave. A-47
A.4.2-9 Indoor vertical floor acceleration due to
the air wave. A-48
B-l Oscillograph record of blast no. 1. B-3
B-2 Oscillograph record of blast no. 2. B-5
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1.0 INTRODUCTION
This research program was designed to compare the exterior blast
noise and vibration environment during a stone quarry blast with
the blast noise and vibration environment produced inside typical
nearby dwellings. It was found that in all cases the ground-borne
vibration from a blast produced more noise and vibration inside than
outside a dwelling. The typical air blast that follows shortly
after the ground wave may produce even more noise and vibration
inside than the excitation from the ground wave. A large choice
of transfer functions was determined to compare the outdoor blast
noise and ground vibration to the indoor noise and vibration for
typical dwellings during a quarry blast.
1.1 Current Information Available on Quarry Blast Noise and
Vibration
At the time this research program was initiated, the blast noise
and ground vibration described by peak-over-pressure and peak
ground velocity measurements were already well understood. The
Bureau of Mines had published several reports containing data
that described the relationship between these peak levels and
the distance,from the blast and the maximum charge per delay of
1 2
the blast. ' These data also showed that peak values correlated
well with structural damage and window breakage. Time history
and frequency spectra measurements have been made of blast noise
and vibration inside and outside of dwellings by the Bureau of
3 4
Mines and Kamperman Associates Inc. These data show that there
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are two separate waves outside (a ground-borne wave and an airborne
wave) and each wave causes both sound and vibration signals within
dwellings.
The effects of weather conditions on the airborne blast wave have
3-5
also been researched previously. At distances of several kilom-
eters from the blast, the temperature gradient, wind speed and
direction, and wind gradient greatly control the peak-over-
pressure. At lesser distances of a few kilometers the wind speed
and direction are the most significant parameters in the propaga-
tion of the air blast beyond the quarry or open pit mine
property.
Studies on the psychological effects of impulse signals such as
7-10
quarry and open pit mine blasting have also been done previously.
The most recent reports on impulse noises suggest that a C-weighted
1-second integration of the sound wave may be used to describe
8 10
the human reaction. ' Human annoyance to vibration correlates
well with peak velocities above 2 to 8 Hz (depending upon the
direction) and peak acceleration below these frequencies. A
frequency-weighted peak acceleration measurement has been proposed
9
by ISO as an approximation to this.
Only limited information has been published on reducing the noise
and vibration from quarry and open pit mine blasting. However,
this information does suggest that improved blasting techniques
produce lower-level sound and ground velocity signals.^
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1.2 Purpose of This Research Study
The purpose of this study was to determine the transfer function
of the outdoor ground wave and air wave produced by a quarry blast
to the indoor vibration and sound found in typical dwellings. The
indoor vibration and sound were to be compared to accepted criteria
descriptors of human annoyance produced by impulsive sound and
vibration. The outdoor signals were to be compared to past measure-
ment descriptors of quarry blasts. Schemes predicting the magnitude
of the blast, given the distance from the blast and the maximum
charge per delay, were also studied to better understand the
overall blast noise and vibration phenomena.
The objective of this study was to research a very small segment
of the overall problem of annoyance to residents inside typical
dwellings arising from blasting activities at nearby stone quarries.
Subjective responses of human annoyance to blasting were not con-
sidered in this study. Health and welfare considerations were
explicitly excluded. The study concentrated only on determining
simple, objective measures to monitor ground-borne vibration and
airborne blast noise outside and predict the noise and vibration
inside a typical dwelling. The indoor and outdoor blast noise
and vibration descriptors were selected to be compatible with the
physical descriptors currently being used by other organizations
concerned with various aspects of blast noise and vibration
phenomena. The organizations of principal concern were: EPA,
ISO, BuMines, CERL, Department of the Army, AMRL/BBA at WPAFB and
HUD. The results of the 1975 quarry blast noise study for Illinois
IEQ are included with the results of this study for EPA.
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2.0 SUMMARY
2.1 Blast Noise and Vibration Descriptors
Determining the transfer function for typical dwellings by measuring
the outdoor blast noise and vibration and comparing it with the
indoor blast poise and vibration can be accomplished in a variety
of ways. The main concern of this study was to select descriptors
that directly related to measurement methodologies already commonly
in use, simple descriptors that would best describe the response
of the dwelling to the blast noise and vibration, and descriptors
that could measure the human annoyance caused by blast noise and
vibration inside dwellings. The descriptors used are outlined in
Tables 2.1-1 and 2.1-2.
Table 2.1-1. Blast Noise Descriptors
1. Peak sound pressure level.
2. Sound pressure time history.
3. Sound frequency spectrum analysis.
4. C-weighted sound exposure level (CSEL).
5. C-weighted sound-level slow meter response.
6. A-weighted sound exposure level (SEL) indoors.
7. A-weighted frequency spectra indoors.
8. 4 to 200 Hz sound exposure level (SEL).
9. 4 to 200 Hz slow meter response.
Note: SEL = sound exposure level, VEL = vibration exposure
level, both normalized to one second.
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Table 2.1-2. Vibration Descriptors
1. Peak velocity vibration level, lateral (radial), transverse,
vertical.
2. Velocity vibration time history.
3. Vector sum of lateral, transverse, and vertical velocity exposure
level (VEL).
4. Lateral, transverse, and vertical velocity vibration frequency
spectrum analysis.
5. Lateral, transverse, and vertical independent velocity vibration
exposure level (VEL).
6. Lateral, transverse, and vertical independent velocity vibration
level slow meter response.
7. Lateral, transverse, and vertical independent velocity vibration
level C-weighted slow meter response.
8. Peak acceleration level, 5.6 Hz low-pass.
9. 5.6 Hz low-pass acceleration VEL indoors.
10. Acceleration vibration frequency spectrum analysis (indoors).
Twenty-six blast events were recorded for this current study, which
also covers an additional 15 blast events recorded by the Illinois
IEQ study of 1975. The total 41 recorded blast events consist of
the 18 blast events recorded by Kamperman Associates Inc. and
Mr. Greg Zak of Illinois EPA, plus an additional 8 by Illinois
EPA for this study, and 15 blast events recorded in 1975 in the
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Illinois IEQ study by a combination of Bureau of Mines,
Kamperirtan Associates Inc. and Illinois EPA.
All the descriptors in Tables 2.1-1 and 2.1-2 were used to
evaluate the blast noise and vibration signals from 10 to 15 of
the blast events recorded in this study.
2.2 Blast Noise and Vibration Measurement Methodologies
Three different measurement systems were utilized to record the
information summarized in this report. The principal measurement
system was a semi-portable (mobile) tape-recording system that
permitted simultaneous recording of eight channels of information
over a frequency range of 0 to 2500 Hz, plus a secondary cassette
recorder used to obtain the A-weighted sound level inside a dwelling
over a frequency range of 25 to 10 K Hz. Three identical velocity-
sensitive transducers were used to monitor the ground vibration
outside a dwelling. The velocity pickups were oriented in the
three mutually perpendicular axes to measure lateral, transverse,
and vertical ground velocity. Two microphone carrier systems,
one located outside the dwelling and one inside, were used to
measure the air blast noise from 0.1 to 2.5 K Hz. Similarly, the
indoor floor vibration was monitored with three mutually perpendicular
mounted velocity transducers identical to the units used outside
the dwelling. Velocity was recorded from these units over a
frequency range of 4 to 1,000 Hz. Occasionally one of the indoor
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transducers would be replaced by an accelerometer with an extended
frequency range of 0.5 to 2,500 Hz.
The second measurement system was a portable air blast tape-
recording system handled by Greg Zak of Illinois EPA. This
system was designed to record the total air blast signal ranging
from 0.6 Hz to 2,000 Hz. The portable blast; noise recording
system was used to record the blast noise on the quarry property
on a line between the blast event and the instrumented dwelling.
In addition, Mr. Zak was able to record blasts from an open pit
coal mine, two silica sand quarries, and an additional limestone
quarry.
The air blast study conducted in 1975 for Illinois IEQ utilized
two principal measuring systems to record the air blast signal on
magnetic tape. The two systems had the same capability as the
portable system used by Illinois EPA and described in the previous
paragraph. Mr. Greg Zak of Illinois EPA supplemented the blast
noise measurements made by Kamperman Associates Inc. in the same
manner for both the 1975 and the 1976 blast noise studies.
The third type of measurement system was operated by the Bureau of
Mines. The Bureau of Mines provided a mobile van with personnel
under the direction of David Siskind from the Twin Cities Research
Center to augment the 1975 Illinois IEQ study. The Bureau of
Mines had the capability of recording up to 12 channels of ground-
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borne and airborne blast data simultaneously. The Bureau of Mines
made two separate visits to the Chicago area to measure blast noise
and vibration inside and outside residential structures during the
3
1975 study. The results of their data have been published and
are incorporated into the findings of this study.
All the blast noise and vibration measurements made during the
1975 Illinois IEQ study and the 1976 EPA study were obtained at
limestone quarries in the Chicago area, with the exception of the
eight additional air blast recordings made by Greg Zak of Illinois
EPA.
2 . 3 Data Reduction Methodologies
The mobile recording system assembled by Kamperman Associates Inc.
for this study was designed to derive all of the descriptors listed
in Tables 2.1-1 and 2.1-2 for the 18 blasts recorded in typical
dwellings instrumented both inside and outside. The methodologies
used to obtain the comprehensive information from these recordings
are contained in Appendix A of this report.
2.4 Selection of Descriptors of Human Annoyance
The annoyance to the residents inside dwellings resulting from
blasting activities is, indeed, a very complex problem. Over the
years, the Bureau of Mines has been principally concerned with
establishing safe limits for air blast and ground vibration to
avoid structural damage to nearby buildings during a blast. With
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Library/Region IV
U.S. Environmental Protection Agency
345 Courtland Street, N.E.
Atlanta, Georgia 30308
the recently increasing population density in the vicinity of
quarries and open pit mines, annoyance to residents inside
dwellings during blasting activities is receiving much more
attention and study. There are no recognized annoyance standards
applicable to blasting at this time. Whether the peak noise or
vibration is more or less significant than the total energy in
the blast event is subject to debate. It is for this reason
that both peak- and energy-type blast noise and vibration descriptors
were utilized in this study (Tables 2.1-1 and 2.1-2).
2.5 Determining the Transfer Function for Blast Noise and
Vibration from Outside to Inside Typical Dwellings
Because of the uncertainties associated with human response to
blasting events discussed in the previous section, it was believed
important to consider many descriptors (see Tables 2.1-1 and 2.1-2)
to arrive at a variety of transfer functions. This wide variety
permits the user of this study to select the blast noise and
vibration descriptors which best meet his needs, and then to
select the transfer function from the outdoor blast noise and
vibration environment and relate it to the indoor blast noise
and vibration environment for the dwellings studied.
2.6 Relating the Magnitude of Blast Noise and Vibration to
Quarry Blasting Techniques
The blast noise level (using different descriptors) was correlated
with the maximum explosive charge weight per delay. A similar
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correlation was made for the ground vibration. Both the air blast
and the ground-borne vibration were then correlated with distance
from the blast.
3.0 CONCLUSIONS AND RESULTS OF STUDY
3.1 Frequency Range of Interest
More than 200 detailed blast noise and vibration frequency spectra
were studied in detail to determine the frequency range of interest
with respect to typical dwellings. Different criteria were estab-
lished to measure the air blast and ground-borne vibration from a
quarry blast.
The ground vibration velocity level spectra measured outside (in
each of the three mutually perpendicular planes) were compared
with similar floor vibration velocity levels measured inside a
specific dwelling. Every dwelling measured contained some
resonances that produced higher vibrations, at certain frequencies,
inside the dwelling than outside in the ground. The frequency
bandwidth containing these resonant frequencies (vibration
amplification) was noted for each dwelling. A composite of
all of the data showed that a measurement bandwidth of approximately
5 to 200 Hz would encompass all of the dwelling resonances due
to ground-borne vibration. The majority of the resonances were
between 10 and 100 Hz.
A slightly different approach was taken in measuring the interior
vibration caused by the air blast signal. The major blast energy
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produced by stone quarry blasting appears at 1 Hz (+0.5 Hz).
At this frequency of maximum pressure, the magnitude of the
1 Hz component is essentially the same inside and outside the
dwelling. However, typical single-family dwellings do not
respond to this 1 Hz component. Therefore, the high amplitude
1 Hz component was considered relatively unimportant to the
residents within dwellings, since they could not hear or feel it.
The next step was to look at all the floor vibration (velocity)
level spectra generated by the air blast alone. It was decided
that the vibration frequency range of interest would be the measured
velocity level bandwidth that was exactly 20 dB below the peak
velocity within the bandwidth. After summarizing all the results,
it was found that the bandwidth meeting this criteria was again
approximately 5 to 200 Hz, with the majority of the measurements
falling between 10 and 100 Hz.
The conclusion is that typical dwellings contain numerous resonant
frequencies throughout the frequency range from 5 to 200 Hz.
These resonances can be readily excited during a blast by either
the ground-borne wave or the air wave.
3.2 Amplitude Measures of Blast Noise and Vibration
Two basic signal amplitude measurement methodologies were used
in this study: the peak level of the blast noise or vibration
and a 1-second equivalent integration of the blast noise or
vibration exposure level (SEL or VEL). The standard (type 1)
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sound-level meter set for slow meter response was also utilized
to approximate the true 1-second integration of SEL or VEL. Sound-
level meters with a 1-second time constant are a standardized
instrument in common use. One-second SEL or VEL instruments have
been built, but are not in common use at this time.
3.3 Human Annoyance Descriptors Applied Inside a Dwelling
There are four signals of major interest inside a dwelling for
each blast event: the noise and vibration produced by the
ground wave, which arrives first, and the noise and vibration
produced by the air blast, which follows shortly after.
Two noise measures appear appropriate, since they can best be
related to previous annoyance studies. These are the C-weighted
SEL (CSEL) and the A-weighted SEL. The C-weighted SEL can be
correlated in a straightforward manner with the magnitude of the
structural vibration of the dwelling resulting from the blast.
The A-weighted SEL can be used to measure non-linear effects such
as rattling of windows, dishes, or bric-a-brac, and effects on
the actual structure of the dwelling.
The non-linear rattling effects are known to occur especially in
cases where the blast noise and vibration are relatively intense.
The prime objective of this study was to determine the transfer
function of outdoor noise and vibration to the indoor noise and
vibration. To accomplish this, most measurements were made at
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a distance of approximately 1000 meters from the blast to enable
one to separate the arrival of the ground wave from the later
arrival of the air blast. In a few situations there were homes
located 1/10 of this distance from the blast event; when this
occurred, an instrumented home 1000 meters from the blast event
did not usually receive sufficient excitation from either the
ground wave or the air blast to cause significant rattling-type
noise inside the dwelling because the blasting levels were limited
by the nearest residence.
A third descriptor for measuring the indoor blast noise might
logically be the peak pressure level. It was pointed out earlier
that the peak pressure level is essentially the same inside and
outside a typical dwelling.
Considerable study has been done on the response of humans to
low-frequency vibration. In the principal frequency range of
interest to this program (5 to 100 Hz), there appears to be a
general consensus that humans are velocity-sensitive. It is not
understood whether peak velocity level or the vibration exposure
level (VEL) is the important descriptor. It has been pointed out
on numerous occasions that the peak velocity level from slamming
a door in a dwelling may be equal to that produced by a quarry
blast. This.was tested and found to be true. However; the
slamming door event had a duration of only 0.01 seconds, while
the typical blast events reported in this study had an average
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duration of approximately 5 seconds (including the air blast) or
500 times longer.
3.4 The Rank Ordering of Outdoor Blast Noise and Vibration
Descriptors That Correlate Best with the Indoor Human
Annoyance Descriptors
Four categories must be considered: (1) the outdoor ground vibra-
tion as it relates to the indoor floor vibration; (2) the outdoor
ground vibration as it relates to the indoor noise caused by the
vibration; (3) the outdoor air blast as it relates to the indoor
noise; (4) the outdoor air blast as it relates to the indoor floor
vibration. A large number of descriptors were analyzed and the
results are presented in this section. A variation of less than 2:1
in the standard deviation is probably not significant due to the
limited data base, which ranged between 10 and 30 data pairs
(typically 15). The following is an abbreviated summary starting
with the first category (see Table 3.4-1). Good correlation
(item 3 in the table) was found by determining the VEL of the
velocity vector sum of the lateral, transverse, and vertical
components outside and relating it to the similar VEL of the
three components on the floor of the dwelling inside (standard
deviation 2.6 dB). A much simpler measurement (items 5 and 6)
can be made by simply utilizing one velocity pickup (with a uni-
form response down to 4 to 6 Hz) and connecting it to the input
of a standard sound-level meter set for flat frequency response
(down to at least 5 Hz) and slow meter response. The velocity
-14-
-------
Table 3.4-1. Rank ordering (by standard deviation) of outdoor
measurement of ground velocity minus indoor measurement
of floor velocity
Outdoor Ground Velocity
(dB re 1 meter per second)
Indoor Floor Velocity
Due to Ground Wave Mean Standard
(dB re 1 meter per second) Difference Deviation
1. Vector Sum 4-200 Hz VEL
2. Maximum Peak of 3 Directions
3. Vector Sum 4-200 Hz VEL
4. Vertical 4-200 Hz VEL
5. Vertical 4-200 Hz Slow
Response
6. Lateral 4-200 Hz Slow
Response
7. Maximum 4-200 Hz VEL
8. Lateral 4-200 Hz VEL
9. Lateral Peak
10. Lateral 4-200 Hz VEL
11. Transverse 4-200 Hz VEL
12. Lateral 4-200 Hz VEL
13. Maximum Peak
14. Lateral Peak
15. Vertical 4-200 Hz Slow
16. Vertical 4-200 Hz Slow
17. Lateral 4-200 Hz Slow
18. Vertical Peak
19. Transverse Peak
20. Lateral 4-200 Hz Slow
21. Vertical C-Wt. Slow
22. Lateral C-Wt. Slow
23. Lateral C-Wt. Slow
Vertical 4-200 Hz VEL +2.3
Maximum Peak of 3 Directions -2.2
Vector Sum 4-200 Hz VEL -1.3
Vertical 4-200 Hz VEL -4.7
Vertical 4-200 Hz VEL -7.0
Vertical 4-200 Hz VEL -3.9
Maximum 4-200 Hz VEL +1.0
Vertical 4-200 Hz VEL -1.4
Vertical Peak -2.2
Lateral 4-200 Hz VEL +0.8
Transverse 4-200 Hz VEL +0.6
Vector Sum 4-200 Hz VEL -4.8
Vertical 4-200 Hz VEL +9.3
Lateral Peak -0.3
Maximum 4-200 Hz VEL +7.6
Vector Sum 4-200 Hz VEL -10.8
Maximum 4-200 Hz VEL +4.1
Vertical Peak -4.1
Transverse Peak +0.1
Vector Sum 4-200 Hz VEL -7.1
Vertical 4-200 Hz VEL -10.1
Vertical 4-200 Hz VEL -8.3
Vector Sum 4-200 Hz VEL -11.8
2.1
2.5
2.6
2.8
2.9
2.9
2.9
3.1
3.2
3.4
3.4
3.4
3.4
3.4
3.7
3.9
3.9
4.0
4.0
4.2
5.3
5.6
7.3
-15-
-------
pickup should measure horizontal ground vibration in the lateral
(radial) or vertical direction. The maximum reading on the sound-
level meter would correlate well with the VEL of the vertical
velocity of the floor inside the dwelling (standard deviation of
2.9 dB). If one is interested in the peak velocity level in any
of the three directions on the floor inside the dwelling, one
should measure in all three directions on the ground outside (2).
The maximum peak level on the ground outside correlates with the
maximum peak level on the floor inside (standard deviation 2.5 dB).
The peak vector sum level of the three mutually perpendicular axes
measuring the ground outside would also be expected to correlate
with the peak vector sum level on the floor inside (standard devia-
tion between 2 and 3 dB), although this was not experimentally
proven because of the difficulties of computing the vector sum
electrically from tape-recorded signals. The simplest method for
determining the peak level of the vertical velocity inside is to
measure the peak level of the lateral (radial) ground velocity (9)
outside the dwelling (standard deviation 3.2 dB).
The second category relates the ground velocity vibration level
outside to the noise generated inside a typical dwelling (see
Table 3.3-2). A measurement of the lateral (radial) ground velocity
vibration level (item 1) with a flat response sound-level meter
(5 Hz and above), and observing the peak reading on slow meter gave
good correlation to the indoor C-weighted SEL (CSEL) (standard
deviation 2.1 dB). The VEL of the vector sum (3) measured on the
-16-
-------
Table 3.4-2. Rank ordering (by standard deviation) of measurements of
outdoor ground velocity level minus indoor sound pressure
level.
Indoor Sound Pressure
Outdoor Ground Velocity Level Level Due to Ground Wave Mean Standard
(dB re 1 meter per second) (dB re 20 U pascals) Difference Deviation
1.
Lateral 4-200 Hz Slow
C-Wt.
SEL
-149.9
2.1
2.
Lateral 4-200 Hz VEL
C-Wt.
SEL
-147.5
2.6
3.
Vector Sum 4-200 Hz VEL
C-Wt.
SEL
-143.8
3.2
4.
Lateral 4-200 Hz VEL
4-200
Hz SEL
-153.2
3.2
5.
Vector Sum 4-200 Hz VEL
4-200
Hz SEL
-150.3
3.3
6.
Transverse 4-200 Hz VEL
4-200
Hz SEL
-154.6
3.5
7.
Vertical 4-200 Hz Slow
C-Wt.
SEL
-153.2
3.6
8.
Lateral Peak
C-Wt.
SEL
-137.2
3.6
9.
Vertical 4-200 Hz VEL
C-Wt.
SEL
-150.9
3.8
10.
Lateral C-Wt. Slow
c-wt.
SEL
-154.5
3.9
11.
Vertical 4-200 Hz VEL
4-200
Hz SEL
-156.7
4.2
12.
Vertical 4-200 Hz Slow
4-200
Hz SEL
-159.8
4.5
13.
Transverse 4-200 Hz VEL
c-wt.
SEL
-149.0
5.0
14.
Lateral Peak
Peak
-156.0
5.4
15.
Transverse Peak
Peak
-157.1
5.7
16.
Vertical c-Wt. Slow
C-Wt.
SEL
-163.1
5.7
17.
Vertical Peak
Peak
-158.1
6.6
Example: (1) A lateral ground vibration, maximum reading and slow response on
a sound-level meter, of -50 dB re one m/s (0.12 in/s) would produce
an indoor noise level of 100 dB CSEL.
-17-
-------
ground outside was correlated with the CSEL inside (standard
deviation of 3.2 dB). To determine the peak noise level inside
(14), one can measure the peak lateral (radial) velocity vibration
level in the ground outside (standard deviation 5.4 dB).
The third category deals with the blast noise outside as it relates
to the noise generated inside (see Table 3.3-3). Good correlation
was obtained by inserting a 4 to 200 Hz filter into the external
filter connections on a type 1 sound-level meter (2) and observing
the maximum response with the slow meter response. This related
to the CSEL inside (standard deviation 2.5 dB). Another choice
is to use a standard type 1 precision sound-level meter set on C-
weight slow meter response (3) and read the maximum outside level
to approximate CSEL inside (standard deviation 2.7 dB). An alternate
choice is to measure CSEL outside (4) re CSEL inside (standard
deviation 2.7 dB) , The SEL measured over the frequency range of
4 to 200 Hz outside correlated (5) with the CSEL inside (standard
deviation 3.5 dB). No measurement outside correlated very well
with the A-weighted noise level inside. The standard sound-level
meter on C-weight slow response max reading (9) correlated with the
indoor A-weighted SEL (standard deviation 6.5 dB).
The fourth category deals with the relationship between the outdoor
air blast and the indoor floor vibration (see Table 3.3-4). In
this situation, an external 4 to 200 Hz 4-pole (24 dB/octave)
band-pass filter on a standard type 1 precision sound-level meter
-18-
-------
Table 3.4-3.
Rank ordering (by standard deviation) of measurements of
outdoor sound pressure level minus indoor sound pressure
level.
Outdoor
Sound Pressure Level
(dB re 20 y pascals)
Indoor Sound Pressure
Level Due to the Air Wave Mean Standard
(dB re 20 y pascals) Difference Deviation
1. Peak
2. 4-200 Hz Slow
3. C-Wt. Slow
4. C-Wt. SEL
5. 4-200 Hz SEL
6. 4-200 Hz SEL
7. Peak
8. 4-200 Hz SEL
9. C-Wt. Slow
10. C-Wt. Slow
11. C-Wt. SEL
Peak
C-Wt. SEL
C-Wt. SEL
C-Wt. SEL
C-Wt. SEL
4-200 Hz SEL
C-Wt. SEL
A-Wt. SEL
A-Wt. SEL
A-Wt. SEL
A-Wt. SEL
-0.9
11.3
2.8
4.3
16.4
-0.5
32.9
46.3
32.9
34.9
35.3
1.6
2.5
2.7
2.7
3.5
3.6
4.8
5.4
6.5
6.5
6.7
-19-
-------
Table 3.4-4. Rank ordering (by standard deviation) of measurements of
outdoor sound pressure level minus indoor floor velocity
level.
Outdoor Indoor Floor Velocity
Sound Pressure Level Level Due to Air Wave Mean Standard
(dB re 20 y pascals) (dB re 1 meter per second) Difference Deviation
1.
4-200
Hz
Slow
Vector Sum 4-200 Hz VEL
166.0
2.9
2.
c-wt.
SEL
Vector Sum 4-200 Hz VEL
160.1
3.6
3.
c-wt.
SEL
Maximum 4-200 Hz VEL
161.7
3.6
4.
c-wt.
Slow
Vector Sum 4-200 Hz VEL
157.6
3.8
5.
c-wt.
SEL
Vertical 4-200 Hz VEL
163.3
4.6
6.
4-200
Hz
Slow
Vertical 4-200 Hz Slow
178.2
4.7
7.
4-200
Hz
Slow
Maximum 4-200 Hz VEL
168.9
5.0
8.
4-200
Hz
SEL
Maximum 4-200 Hz VEL
173.6
5.2
9.
4-200
Hz
SEL
Maximum Peak
162.4
5.2
10.
Peak
Maximum Peak
178.2
5.2
11.
Peak
Vector Sum 4-200 Hz VEL
186.8
5.3
12.
4-200
Hz
Slow
Maximum Peak
157.8
5.8
13.
4-200
Hz
SEL
Transverse 4-200 Hz VEL
184.2
6.0
14.
4-200
Hz
Slow
Vertical 4-200 Hz VEL
169.0
6.2
15.
c-wt.
Slow
Maximum Peak
149.1
6.2
16.
Peak
Transverse Peak
188.9
6.3
17.
c-wt.
SEL
Maximum Peak
152.3
6.4
18.
c-wt.
Peak
Maximum Peak
163.6
6.6
19.
4-200
Hz
SEL
Vector Sum 4-200 Hz VEL
173.5
7.3
20.
4-200
Hz
SEL
Vertical 4-200 Hz VEL
176.1
7.8
21.
c-wt.
Slow
Vertical 4-200 Hz VEL
153.6
7.8
22.
Peak
Vertical 4-200 Hz VEL
190.1
8.1
23.
Peak
Vertical Peak
180.7
8.3
24.
Peak
Lateral Peak
185.7
8.5
25.
4-200
Hz
SEL
Lateral 4-200 Hz VEL
180.4
9.1
Example: (2) An outdoor blast of 100 dB CSEL would shake a dwelling floor at
-60 dB VEL re one m/s.
Example:(15) An outdoor blast of 100 dB C-weighted maximum slow meter response
would shake a dwelling floor at -49 dB re one m/s (equal to 0.14 in/s).
-20-
-------
on slow response read outside, correlated well (1) with the vector
sum of the velocity VEL of the floor velocity inside (standard
deviation 2.9 dB). Another choice was CSEL outside (2) relative
to the vector sum 4 to 200 Hz velocity VEL inside (standard devia-
tion 3.6 dB). The simplest measurement was to use the standard
C-weight slow response precision sound-level meter outside (4)
to relate to the vector velocity VEL of the floor vibration inside
(standard deviation 3.8 dB). It was interesting to find that the
SEL of the outdoor air blast measured in the bandwidth of 4 to 200 Hz
(18) compared with the vector sum VEL over the same frequency range
for the floor velocity gave a rather wide standard deviation of
7.3 dB.
The peak sound pressure level outside compared (9) to the maximum
peak velocity level in any direction on the floor inside gave a
standard deviation of 5.2 dB. The peak sound pressure level outside
correlated (10) with the indoor floor velocity vector sum VEL for
a standard deviation of 5.3 dB.
3.5 Comparison of Outdoor Air Blast Descriptors
It has been common practice to describe blast noise in terms of
the peak-over-pressure in the air. Table 3.5-1 shows how different
outdoor blast noise measurement descriptors relate to each other.
All air blasts recorded for the EPA study are included in this
table.
-21-
-------
Table 3.5-1. Comparison of outdoor air blast descriptors (descriptor A
minus descriptor B)• Sound levels in dB re 20 |i pascals.
Descriptor A
Descriptor B
Mean
Difference
Standard
Deviation
Peak Sound Level
C-Weighted SEL
25.6
5.8
Peak Sound Level
C-Weighted Slow Meter
27.3
5.7
Peak Sound Level
4-200 Hz SEL
16.3
3.8
Peak Sound Level
4-200 Hz Slow Meter
19.9
4.6
4-200 Hz SEL
C-Weighted SEL
8.6
4.2
4-200 Hz SEL
C-Weighted Slow Meter
10.4
4.2
C-Weighted SEL
C-Weighted Slow Meter
1.7
2.1
4-200 Hz SEL
4-200 Hz Slow Meter
3.6
2.2
-22-
-------
3.6 The Importance of the One Hertz Air Blast Peak
Four blast events were recorded with an accelerometer mounted
directly on top of a velocity transducer. Both transducers were
oriented to measure vertical floor motion. The purpose of this
experiment was to confirm that the air blast with its very strong
1 Hz (+ 0.5 Hz) frequency component had little influence on the
response of typical dwellings. Table 3.6-1 contains the results
7 i
of the ISO draft recommendation (5.6 Hz low-pass filter) accelera-
tion measurement experiment. VEL was used instead of peak accelera-
*
tion as recommended by ISO. For the purpose of this discussion
either peak or VEL is satisfactory. The large number of floor
velocity frequency spectra measured and analyzed showed that a
typical dwelling did not respond to an air blast below approximately
5 Hz. The "typical dwelling" referred to throughout this report
is a single-family one- or two-story structure with a basement.
Table 3.6-1 shows that increasing the measurement bandwidth to
frequencies below 4 Hz (to 0.5 Hz) had little effect on the measured
floor vibration (except for blast no. 14) even though the air blast
is most intense at 1 Hz. Thus, for typical dwellings, the ISO
frequency-weighted acceleration measurement is equivalent to a
velocity measurement where one meter per second squared (frequency
weighted) equals 1.1 inches per second velocity.
The data in Table 3.6-1 include only the air blast por.tion of the
blast event. The ground wave does not contain blast energy below
5 Hz.
-23-
-------
Table 3.6-1 Integrated energy of vertical floor acceleration according
to ISO recommendations with further frequency filtering.
Blast No.
Filter
Bandwidth
14*
15
dB re
16
1 g VEL
17
0.5 Hz - 1000 Hz
-66.0
-
-
-
0.5 Hz - 50 Hz
-66.0
-56.5
-65.4
-69.0
1 Hz - 50 Hz
-66.8
-56.7
-65.4
-69.0
2 Hz - 50 Hz
-68.4
-57.4
-65.4
-69.0
4 Hz - 50 Hz
-72.6
-57.5
-65.4
-69.0
5 Hz - 50 Hz
-73.0
-57.5
-65.4
-69.0
5 Hz - 100 Hz
-73.0
-
-65.4
-69.0
*Note that blast no. 14 was measured in a large, stiff concrete structure
more typical of a dormitory, office, or concrete apartment building than
of a single-family dwelling.
-24-
-------
Blast no. 14 was recorded on the second floor of a two-story
concrete office building with exterior plan dimensions of nearly
100 meters. None of the blast 14 test results were included in
the transfer function comparisons in Tables 3.3-1 through 3.3-4.
The test results obtained from the concrete office buildings were
very different from the results obtained from the single-family
dwellings, as Table 3.6-1 shows. It is clear that an air blast
would have greater impact on large, stiff (concrete or block)
structures such as domitories, hotels and hospitals.
3.7 Predicting the Amplitude of Quarry Blast Noise and Vibration
The peak velocity level of the ground wave correlates to the distance
and maximum explosive charge by the relationship
20 log v = 20 log H + 20 (8) log (
W'
where H and 0 are constants determined by the orientation of the
face and the rock formation and soil composition surrounding the
quarry. Many of the blast velocity level measurements made during
this study and the 1975 study were taken at quarries close enough
to each other to have similar decay rates. By examining the decay
rates of each quarry it was found that the quarries could be com-
bined into three groups. These data are plotted in Fig. 3.7-1.
In Bulletin 656, the Bureau of Mines shows that ground velocity
data taken at different quarries (in different parts of the
country) cannot be combined to form a ground propagation law.
In the six limestone quarries cooperating with Kamperman Associates Inc.
-25-
-------
Fig. 3.7-1. Velocity Levels versus Scaled Distance
Quarry group 1: O — Peaks
Quarry group 2: & — Peaks, ~— 4-200 Hz VEL
Quarry group 3: ^ — Peaks, O— 4-200 Hz VEL
C
O
O
V
w
u
Q)
&C:
V
H c
<1) o
•P O
^
CO
m
a)
>i
4->
¦H
U
o
I—I
(I)
>
-60
(.0394)
-80"
(.00394)
10
(22.1)
100
(221)
Scaled distance in meters/k gram
1/2
(feet/pounds )
100
(221
1/2
-26-
-------
for blast measurements, it was found that quarries very near to
one another (within a few kilometers) did have the same propagation
rate but those separated by several kilometers had quite different
propagation rates. The data in Fig. 3.7-1 were, therefore,
separated into three groups of quarries. Only peak ground
velocity level was measured in group 1. Both peak and 4 to 200 Hz
vector summed VEL ground velocities were measured in groups 2 and
3, but only one shot was measured in group 3. The ground velocity
level data from group 2 show that the line describing the 4 to
200 Hz ground velocity vector sum VEL is parallel to the line
describing the peak ground velocities from the same group, but
lies approximately 8 dB lower. The error bar shown for the vector
sum VEL data is smaller than the error bar (standard deviation)
shown for the peak ground velocity level data.
The peak sound pressure level (P) can be correlated with the ratio
of the distance from the blast (D) divided by the cube root of the
maximum explosive charge per delay (W). This correlation can be
expressed as
20 log P = 20 log K + 20 (8) log (-^ryr)
W 7
where K and 0 are constants depending on the orientation of the
face and the particular weather conditions.
The peak sound pressure levels plotted against the distance divided
by the cube root of the maximum charge weight are shown in Fig. 3.7-2.
-27-
-------
Fig. 3.7-2. Sound Levels versus Scaled Distance
Downwind in front of face: ¦ — Peaks, ~ — 4-200 Hz SEL
Downwind behind face and
crosswind in front of facerO— Peaks, • — 4-200 Hz SEL
Crosswind behind face: £— Peaks, ^ — 4-200 Hz SEL
(25) (250) (2500)
Scaled distance in meters/k grams'^3
(feet/pounds*^3)
-28-
-------
These measurements (41 blasts) were made at seven limestone
quarries, two silica sand quarries, and one open pit coal mjne.
To form a close-fitting straight line (linear regression) the
peak levels were divided into three groups. The highest group
consists of data taken downwind and in front of the face. These
data show a decay with distance of slightly less than inverse
square spreading (20 dB per decade of distance). The lowest group
consists of data measured under no-wind or crosswind conditions
behind the face of the blast. These data show slightly more than
inverse square spreading due to access attenuation from the wind.
The data falling in the middle measurements were made downwind
and behind the face or a few points in front of the face and cross-
wind (or no-wind). These data are nearly exactly 20 dB decay per
decade increase in distance. The 4 Hz to 200 Hz SEL measurements
are also plotted in Fig. 3.7-2 for the same three groups and give
the same decay rates with distance as the corresponding peak
data. Four data points remain (two peak levels and two SEL measure-
ments) that are excessively high. These measurements were made of
blasts that had gas leaks and were initiated by primacord. The
straight lines describing the three groups of SEL data have nearly
the same slopes as the straight lines describing the corresponding
peak levels, but they fall between 14 and 18 dB lower than the peak
levels. The error bars drawn for the SEL values are smaller than
those drawn for the peak values.
The C-weighted slow meter responses from all outdoor measurements
made during this study and the 1975 IEQ study have also been
-29-
-------
correlated to the charge weight and distance by the same relation-
ship used to correlate the peak and 4 to 200 Hz SEL. These results
are shown in Fig. 3.7-3. These data give a more gradual decay with
distance than do the peak and 4 to 200 Hz SEL. In fact, these data
show less attenuation with distance than simple inverse square
spreading would predict. This problem is probably due to the
error in the slow meter response system in accurately detecting
this type of impulse signal'.
Similar correlations have been drawn for the 4 to 200 Hz slow meter
response and the C-weighted SEL. These data are presented in Fig.
3.7-4. The slow meter response for a 4 to 200 Hz filter also
shows a decay rate with distance more gradual than would be pre-
dicted by inverse square spreading. The C-weighted SEL data
displays exactly 20 dB per decade change in distance.
A number of conclusions can be drawn from the results of this
study with respect to the magnitude of the air blast and ground
vibration from a blast event:
(1) Neighbors downwind from the blast will experience levels
between 10 dB and 15 dB higher than neighbors crosswind
from the blast (or those under no-wind conditions).
(2) Neighbors in front of the face of the blast will experience
levels between 5 dB and 10 dB higher than those behind the
face of the blast (or in the case of a lift shot).
(3) The blasting methodology is very important in controlling
-30-
-------
Sound Levels versus Scaled Distance for C-Weighted Slow Response
Downwind in front of face: °
Downwind behind face and cross-
wind in front of face:
Crosswind behind face:
~
O
100
(250)
Scaled distance in meters/k grams
(feet/pounds^^)
1000
(2500)
1/3
-31-
-------
Fig. 3.7-4. Sound Levels versus Scaled Distance
Downwind in front of face: A 4-200 Hz Slow
Downwind behind face and
crosswind in front of face:H — 4-200 Hz Slow, O — C-Weighted SEL
(25) (250) (2500)
!/3
Scaled distance in meters/k grams
1/3
(feet/pounds )
-32-
-------
the blast noise and vibration emitted to the neighbors.
(4) The 4 to 200 Hz SEL or CSEL can be predicted from the distance,
explosive charge weight per delay, wind direction, and
orientation to the face at least as well as from the peak-
over-pressure measure.
(5) Although data from every quarry confirm the general principle
that log velocity level (ground vibration) is inversely
proportional to log distance per square root of charge, each
quarry may have a different slope and intercept to the line
describing this propagation rate.
(6) Quarries within a few kilometers of each other may have
exactly the same propagation rate for the ground wave.
(7) The 4 to 200 Hz VEL of the vector sum of the ground velocity
level can be predicted at least as well as the peak ground
velocity level from the distance and the explosive charge
weight per delay, as well as from previous knowledge of the
quarry.
3.8 General Observations
All peak ground velocity data measured outside during this study
and the 1975 study were well below the damage criterion of -26 dB
re 1 m/sec (2 inches/second). All but one peak air blast over
pressure level measured during these two studies were also below
2
the lowest damage criterion of 140 dB re 20 y pascals (0.028 psi).
The one blast over pessure that was in excess of 140 dB was measured
-33-
-------
on the property of an open pit coal mine. Therefore, all blasts
measured may be considered to be in the annoyance range (or lower)
but not a damage risk to dwellings. All basts were both heard
and felt by monitoring personnel, but some low-level blasts passed
by unnoticed by the residents, who were unaware of the exact time
of the blast.
4.0 RECOMMENDATIONS
Section 3.4 discusses a wide variety of noise and vibration descriptors
that may be utilized to determine the transfer function of a quarry
blast from measurements performed outside a typical dwelling to the
blast noise and vibration expected inside the dwelling. After com-
pletion of the field measurements, a further study was made of
descriptors that would correlate best with the blast noise and
vibration produced by a quarry blast. Until this time, it has
been common practice to measure the peak ground velocity in the
three mutually perpendicular axes (or peak vector sum of the three
axes) and the peak-over-pressure of the air blast during a quarry
blast event. The Bureau of Mines'*' has related the peak air blast
over pressure and the peak ground velocity to the maximum charge
weight per delay in the blast. The data obtained on the current
EPA study fit the Bureau of Mines scaling models very well. It
was also discovered that the velocity vector sum 4 to 200 Hz VEL
fitted the Bureau of Mines scaling methodology for ground vibration
better than did the peak ground velocity. The CSEL or 4 to 200 Hz
SEL fit the Bureau of Mines scaling model better than did the
-34-
-------
peak-over-pressure of the air blast. Other descriptors such as
C-weight slow meter response, and 4 to 200 Hz slow meter response
were also compared to the Bureau of Mines scaling model and found
to be somewhat less accurate for both the ground vibration and
the air blast. Thus, in selecting descriptors for determining
the transfer function of a typical dwelling, one should also be
aware of some of the limitations of relating the measured descriptors
to the blast event itself.
4.1 Suggestions for Monitoring Blasting Events with Respect to
Annoyance of Residents in Typical Dwellings
It is not at all clear whether the peak or the total energy density
(SEL or VEL) contained in the blast noise and dwelling vibration
is the more annoying to the residents within the dwelling. This
subject was not addressed in the current study. Wherever possible,
one measurement descriptor was suggested in Section 3.4 to permit
one to predict the peak vibration, or noise response of the
structure, and another descriptor to predict the energy density
(VEL or SEL) within the structure. For air blast measurements,
CSEL or, as a second choice, C-weight type 1 slow response is
recommended. For ground-borne vibration measurements, 4 to 200 Hz
vector sum VEL or, as a second choice, vertical or lateral 4 to
200 Hz type 1 slow response is recommended.
-35-
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4.2 Future Research Needed to Formulate a Blast Noise and Vibration
Regulation
It can be seen from the results of this very limited study that
much more is now known than previously about the response of
typical dwellings to the blast noise and vibration associated with
stone quarry blasting activities. However, this is only a very
small part of the overall blast noise and vibration problems that
affect residents exposed to large blast events.
4.2.1 Psychological Studies for Long Duration Impulses
Probably the least understood area in the blast noise and vibration
phenomenon is the response of residents in dwellings subjected to
the blasting activities of a nearby quarry or open pit coal mine
during blasting events. It has been stated correctly that the
peak vibration in a dwelling caused by the hard slamming of a door
may equal or exceed the peak velocity (measured in the floor of
a dwelling) resulting from blasting activity at a nearby quarry
or open pit mine. A door slamming event is over within approximately
0.01 seconds. A typical quarry blast accompanied by a strong air
blast continuously shakes a dwelling for a period of 5 seconds or
more. Bub since the blast event causes the dwelling to shake
5C0 times longer than the slamming of a door, a measurement of
peak floor velocity alone would probably prove insufficient in
attempting to correlate these two events with human annoyance.
The current study also indicated that a blast containing a broad
frequency range both in the ground-borne and airborne waves can
result in strong sinusoidal motion of the floor inside a dwelling.
-36-
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The question must be raised as to whether the annoyance is the
same for sinusoidal motion versus broadband excitation having the
same peak value or SEL or VEL value.
Another area of interest is the importance of the structure-borne
vibration sensed by a resident versus the inside airborne noise
generated by the shaking of the structure. What are the relative
effects of these various blast-generated stimuli in startling and
annoying residents?
g
As a tentative criterion, CHABA Working Group 69 has proposed a
frequency-weighted peak acceleration (5.6 Hz single-pole low-pass
filter) measurement of ground vibration in the three planes. Above
10 Hz, the CHABA methodology gives a constant conversion factor
2
of one m/s = 1.1 in/s velocity. Below 10 Hz, the CHABA method
is less sensitive than velocity.
4.2.2 Effects on Various Blasting Configurations
The Bureau of Mines, quarry associations, and independent quarry
operators have experimented over the years with a variety of
blasting techniques to minimize air blast and ground-borne
vibration. Most of this work was aimed at minimizing structural
damage to dwellings and other nearby buildings during blasting.
Peak ground velocity and peak-over-pressure were found to be good
descriptors of structural damage. However, the blast noise and
vibration levels which constitute an annoyance problem are probably
of one order of magnitude below the levels which cause structural
-37-
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damage. Therefore, relating peak-over-pressure and peak ground
velocity to the maximum charge weight per delay may not provide
the best measure of annoyance to residents.
The rock and soil conditions surrounding a quarry operation deter-
mine the rate at which the ground vibration decays with distance.
After this decay rate has been determined for a specific quarry,
the scaling rules suggested by the Bureau of Mines can be applied.
Sound propagation of the blast wave is not dependent upon the
ground construction but is highly dependent upon the weather con-
ditions immediately above and around the blasting operation. The
blast propagation is most intense in front of the face (assuming
it is a well controlled blast and no excess gas escapes either
through the face or through "rifling", which is blowing the
stemming out of the blast hole). More work needs to be done to
determine the role of direction as a function of frequency of the
sound propagation from the face being blasted. The results of
the current study suggest that wind directions play a more
significant role in the sound propagation of blast noise from
the quarry than any other weather factor. This is a tentative
conclusion that needs much further exploration.
All blasts monitored in homes during this study were well controlled
to ensure that no "rifling" or "blowouts" occurred. Quarries in
metropolitan areas are forced to carefully control their blasts
to minimize complaints and avoid law suits. However, one quarry
-38-
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and a few open pit coal mine blasts that were monitored were far
from any residents and therefore not subject to controlled blasting
techniques. Hole blowouts were noticed for two such measurements,
but were monitored only on the quarry or mine property since no
home existed nearby.
Fig. 4.2.2-1. Time history of blast
prior to blowout (.2 sec time elapsed).
Fig. 4.2.2-2. Frequency spectrum of
blast prior to hole blowout. Full
scale 120 dB, frequency range 0 to
1000 Hz.
NOT REPRODUCIBLE
The importance of controlled
blasting is shown in Figs.
4.2.2-1'through 4.2.2-4.
Figure 4.2.2-1 is the time
history of the first part of
a stone quarry blast with its
corresponding frequency spectrum
("F" is 0 to 1000 Hz, "dB" is
60 to 120 dB re 20 y pascals)
shown in Fig. 4.2.2-2. The
rest of the time history of
this same blast is shown in
Fig. 4.2.2-3. The sharp rise
time in this time history is
caused by a hole blowout. The
increased high-frequency energy
caused by this blowout is shown
in the corresponding frequency
spectrum (from 0 to 1000 Hz)
in Fig. 4.2.2-4. Comparison
-39-
-------
Reproduced lrom
best availab|e_S££L-
Fig. 4.2.2-3. Time history of blast,
including hole blowout (0.2 seconds
total time elapsed).
Fig. 4.2.2-4. Frequency spectrum of
blast:, including hole blowout. Full
scale 120 dB, frequency range 0 to
1000 Hz.
of the two frequency spectra
before and after the hole
blowout suggests that the
low-frequency (1 Hz) component,
which is inaudible and has no
effect on dwellings, is not
affected by the blowout, but
the higher frequencies (up to
1000 Hz), which shake dwellings
and are audible, have increased
from 5 dB to 10 dB. The
instantaneous peak of this
shot as determined by the time
histories was not noticeably
increased by the blowout. This
suggests that the instantaneous
peak value is not a good descrip-
tor either for human annoyance
or response of dwellings,
especially for poorly confined
blasts.
I
i
si
i i
m
II
fc a
y
u
y
m
y
-40-
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4.2.3 Economic Impact Versus Blast Noise and Vibration Control
Some stone quarries actively blasting in the vicinity of densely
populated areas have demonstrated that it is economically feasible
to utilize a blasting procedure that results in minimum complaints
from nearby residents. Other quarries consistently produce com-
plaints from their blasting activities. For this reason the
entire problem area of cost-benefit for different quarry operation
needs to be satisfied.
4.2.4 Determine the Transfer Function for a Broader Range of
Living Quarters
The present study considered only typical single-family dwellings,
with the exception of one instrumented structure, which was a much
larger two-story office building. This concrete structure was
found to be more responsive to blast noise and ground-borne
vibration (see Section 3.6). Of particular concern are hospitals,
dormitories, hotels, etc.
-41-
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REFERENCES
Nicholls, H. R., Johnson, C. F., and Duvall, W. I., "Blasting
Vibrations and Their Effects on Structures," U. S. Department
of the Interior, Bureau of Mines Bulletin 656, 1971.
Siskind, D. E. and Summers, C. R., "Blast Noise Standards
and In" f-.rumentation, " Bureau of Mines Technical Progress
Report TPR78, May 1974.
Siskind, D. E., Stachura, V. J., and Radcliffe, K. S., "Noise
and Vibration in Residential Structures from Quarry Production
Blasting: Measurements at Six Sites in Illinois," U. S.
Department of the Interior, Bureau of Mines, Report of
Investigations 8.168, 1976-
Kamperman Associates Inc., "Quarry Blast Noise Study,"
Institute of Environmental Quality, December 1975.
Reed, J. H., "Airblast Prediction Instructions Tooele Army
Depot Munitions Disposal," Sandia Laboratories, June 1975.
Andrews, A. B„, "Air Blast and Ground Vibration in Open Pit
Mining," E. I. duPont de Nemours and Company.
Draft Proposal - "Vibration and Shock Limits for Occupants
in Buildings," August 1975, Document ISO-TC-108/SC4/Secretariat
14/25.
U. S. Environmental Protection Agency, Office of Noise Abate-
ment and Control, "Information on Levels of Environmental
-------
Noise Requisite to Protect Public Health and Welfare with
an Adequate Margin of Safety," 550/9-74-004, March 1974.
9. December 1976 Draft of CHABA Working Group 69, "Guidelines
for Preparing Environmental Impact Statements on Noise."
10. Young, J. R., "Measurement of the Psychological Annoyance
of Simulated Explosion Sequences (Second Year)," Stanford
Research Institute, February 1976.
11. Siskind, D. E. and Stachura, V. J., "Recording System for
Blast Noise Measurement," Sound and Vibration, March 1977.
-43-
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APPENDIX A
DETAILS OF QUARRY BLAST NOISE STUDY
A.1 Measurement Objectives
The overall objective of this research program was to determine
the transfer function of a typical home or dwelling for the
airborne noise and ground-borne vibration observed outside and
inside a typical dwelling during a quarry blast event. This
current research program was a follow-on of the study conducted
by Kamperman Associates Inc. in 1975 for the Illinois Institute
of Environmental Quality on quarry blast noise.
At the outset of the current research program, a one-day meeting
was held at Twin Cities Mining Research Center, Bureau of Mines,
St. Paul, Minnesota on July 15, 1976. Representatives (18) from
many organizations interested in the blast noise problem were
present at this meeting. The one interested person who could not
attend was Mr. David Siskind of the Bureau of Mines office at
Twin Cities Mining Research Center.
The Bureau of Mines field group under David Siskind worked actively
with Kamperman Associates Inc. on the blast noise study of 1975
for Illinois IEQ. A similar close relationship had been planned
for the current research study. However, the tight schedule of
the current study and the prior commitments by the Bureau of
Mines for use of their field measuring instruments effectively
A-l
-------
ruled out any assistance from the Bureau. Throughout the 1975
study for Illinois IEQ, the Bureau of Mines under David Siskind
made all the vibration measurements and a high percentage pf the
airborne blast measurements. Kamperman Associates Inc. and
Illinois EPA made supplementary airborne blast measurements to
obtain a better understanding of the blast noise phenomenon.
Since the Bureau of Mines was unable to assist in the current EPA
blast noise research program, Kamperman Associates Inc. presented
an alternative measurement system approach that would supply the
basic data needed to fulfill the objectives of the study.
A.1.1 Blast Noise and Vibration Parameters to Be Measured and
Studied
A consensus agreement was reached at the July 15, 1976 meeting
on the different measurements to be tape-recorded for the EPA
quarry blast noise study. Ground vibration measurements would be
made immediately outside a dwelling of interest. The ground
vibration would be measured with velocity-sensitive transducers
attached to a concrete slab (not connected with the dwelling) to
measure vibration in the three mutually perpendicular axes:
lateral (often referred to as radial), transverse, and vertical.
The blast noise would be measured both outdoor and inside the
dwelling of interest. Inside the dwelling, velocity measurements
supplemented by some acceleration measurements would be made of
the floor motion (plus some consideration for wall vibration).
A-2
-------
Typically this would be a measurement in the middle of a room
on either the first or second level (where the latter was possible).
In addition, it was requested that the A-weighted sound level inside
the dwelling be measured during a blast. All data was recorded
on magnetic tape for analysis in the laboratory after each
recorded event.
A.1.2 Frequency Range of Interest
At the Bureau of Mines planning meeting of July 15, 1976, it was
concluded that the frequency range of interest for measuring ground-
borne vibration from quarry blasts could be adequately covered
with a system responding from 5 to approximately 200 Hz. This
frequency range would adequately cover the ground excitation
from a quarry blast and include the structural resonances of
interest in a typical dwelling.
The results of the study done for IEQ in 1975 revealed that the
acoustic signal from the air blast had its peak energy at approxi-
mately 1 Hz. The outcome of the planning meeting at the Bureau
of Mines suggested that the strong 1 Hz acoustic component should
be tape-recorded even though the information of primary interest
would probably be the higher frequencies that coincided with the
7
structural resonances m the dwelling. The ISO document on
human response to vibration suggests that the primary frequency
range of interest is from 1 to 80 Hz. The sound-level spectrum
of principal importance inside a dwelling during a blast was the
A-3
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C-weighted sound level supplemented by A-weighted sound-level
recordings also obtained inside the dwelling. Various outdoor
blast noise descriptors were to be explored to determine the
best transfer function from the outdoor blast noise to the
indoor blast noise and resultant vibration.
A.1.3 Dynamic Signal Range of Interest
The blast measurements for the 1975 IEQ study showed that the
maximum ground velocity inside or outside a dwelling was approxi-
mately .025 meters per second or 1 inch per second (0 to peak).
For the current EPA study, it was assumed that the ground vibration
levels would be somewhat less than the vibration levels observed
during the IEQ study due to the increased distance between the
quarry blast and the monitoring location. A dynamic range for
the velocity measurement was selected to encompass 0.00003 to
0.0 3 meters per second. The indoor acceleration dynamic range
was set for 0.001 to 1 g. The indoor and outdoor sound pressure
measurements were set to cover the range from 70 to 130 dB re
20 y pascals. The A-weighted indoor sound-level meter was set
to record the A-weighted sound level from 50 to 90 dB.
A.1.4 Selection of Measuring Transducers
Velocity-sensitive transducers were chosen to measure the vibration
associated with each recorded quarry blast. Velocity-sensitive
transducers have no particular advantage over acceleration-sensitive
transducers. Velocity pickups have a high sensitivity and a low
A-4
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output impedance and thus relatively long signal cables can be
utilized between the vibration transducer and the tape recorder
without the need of a special preamplifier at the transducer.
Velocity transducers utilize a moving coil operating above its
resonant frequency. The piezoelectric accelerometer utilizes a
ceramic and internally attached mass that produces an output signal
proportional to acceleration below the resonant frequency of the
accelerometer. Velocity transducers are relatively bulky and can
only be utilized for measuring motion in one plane (without re-
adjusting the coil suspension system). On the other hand, accelerom-
eters are relatively small and lightweight and can be mounted to
measure acceleration in any plane perpendicular to the base of the
accelerometer.
The velocity transducers utilized for the current EPA project had
a natural resonant frequency of 4.5 Hz. They were Geo Space model
HS-1. A 470 ohm resistor was applied directly across the output
terminals of the velocity transducer to critically damp the resonance
frequency at 4.5 Hz. This provided an effective output impedance
of approximately 150 ohms for each of the velocity transducers.
Seven of these velocity transducers were used on the project. All
the velocity transducers had the same sensitivity of 23 dB (+ 0.25
dB) re 1 volt at 1 meter per second.
It has been demonstrated that quarry blasts produce ground
vibration in the frequency range above 5 Hz. Experience has
A-5
-------
shown that structural resonances in typical dwellings are also
in the frequency range above 5 Hz. However, the air blast pro-
duced by a quarry can have a very strong component around 1 Hz
and thus it was determined that some measurements of floor vibra-
tion in typical dwellings should be made to observe the influence
of the 1 Hz-dominated air blast on the response of the dwelling.
A GenRad type 1560--P54 accelerometer was utilized to record the
motion of the floor vibration down to 0.5 Hz. The output of the
accelerometer was fed directly into a GenRad type 1933 microphone
preamplifier that had been modified to permit the extended low
frequency response.
To faithfully record the peak value of the .1 Hz component associated
with the blast noise, it was important to have a microphone system
with a frequency response extending approximately one decade below
the lowest frequency of interest. The Bruel & Kjaer type 2631
microphone carrier system equipped with a type 4145 condenser
microphone was utilized to measure the blast noise immediately
outside and inside the particular dwelling of interest. The two
low-frequency carrier systems were loaned to Kamperman Associates Inc.
for the EPA blast noise measurement program. One unit was supplied
by Dr. Paul Schomer (USA-CERL-EV, Champaign, Illinois), and the
other unit by LTC. Daniel Johnson (AMRL/BBA-WPAFB, Dayton, Ohio).
GenRad type 1971 ceramic microphones were also utilized to supple-
ment the Bruel & Kjaer carrier microphone system. The ceramic
microphones were selected to have a good low-frequency response
A-6
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of not more than 3 dB down at 0.5 Hz when connected to the GenRad
type 1933 microphone preamplifier.
The photograph in Fig. A.1.4-1 illustrates most of the noise and
vibration transducers utilized in this study. The right half of
the photograph contains the sound-measuring instrumentation plus
calibrators and windscreens. The left half of the photograph
illustrates the vibration-measuring transducers and a laboratory
vibration calibrator in the background. The small box located
in the lower left corner of the photograph contains the battery
power supply for the GenRad 1933 preamplifier shown between the
battery box and the accelerometer. A similar power supply and
preamp was used with the special low-frequency ceramic microphones.
Six velocity transducers are shown in Fig. A.1.4-1. The velocity
Fig. A.1.4-1 Blast noise and vibration-measurement transducers.
A-7
-------
transducers are mounted in two seismic cages. They are mounted
to measure lateral (radial), transverse, and vertical floor motion.
The seismic cage configuration was always utilized for the outdoor
ground velocity measurements. This configuration was also utilized
for indoor floor measurements plus supplemental measurements with
velocity pickups on the accelerometer. In a few rare instances
the floors inside a monitored dwelling contained wall-to-wall
carpeting, which made secure attachment of the vibration pickup
to the floor virtually impossible. In these instances, individual
transducers were placed on the carpet and a heavy mass, such as the
25-pound bag of lead shot shown in the upper left corner of Fig.
A.1.4-1, was placed on top of the transducer to insure that each
transducer followed the motion of the floor and was not isolated
by the resiliency of the carpet under the transducer.
The two sound-level meters in the background of Fig. A.1.4-1 were
used to record each blast event in this program. The sound-level
meter on the left is a GenRad type 1981 modified to record the
maximum C-weighted sound level on its built-in digital display.
This instrument was used to record the blast noise outside the
dwelling. This measurement was made in addition to the microphone
signal recorded on tape. The sound-level meter on the right is
a modified GenRad type 1565B eguipped with an electret condenser
microphone. This instrument was selected to measure and record
on tape the A-weighted blast noise inside the dwelling. It was
anticipated that the 1 Hz blast component would be 40 to 60 dB
A-8
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above the A-weighted sound level. For this reason it was essential
to select an instrument that performed the A-weighting function
before any amplification, to avoid potential overload of the A-
weighted recording due to excessive low-frequency energy.
A.1.5 Selection of Data-Recording Instruments
To meet the measurement objectives of the EPA quarry blast study,
it would have been ideal to use a tape recorder with a minimum
of nine data channels covering a frequency range from 0.1 Hz to
10,000 Hz and possessing a very wide dynamic range. The recording
problem was solved by leasing a new Hewlett Packard type 3968A
eight-channel FM tape recorder. All of the sound and vibration
measurements could be accommodated with a recorder having a band-
width of 0.1 to 1,000 Hz, except the A-weighted sound level measured
inside the dwelling. To solve this latter problem, the output
signal from the A-weighted sound-level meter was fed directly
into a portable cassette data recorder (Sony TC-152). The
instruments used in the field (and in the laboratory) are shown
in the photograph in Fig. A.1.5-1. The actual electrical hookup
or connection between the various sound- and vibration-measuring
transducers and the recording instruments is illustrated in block
diagram form in Fig. A.1.5-2. The oscilloscope, a multimeter
(DVM), and a 1 volt square wave generator are shown on the left
side of Fig. A.1.5-1. These instruments were part of the field
calibration and trouble-shooting equipment that were relied on
heavily to avoid obtaining erroneous or useless recorded information.
A-9
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" —i
W^%-
Fig. A.1.5-1 Blast noise and vibration-recording instruments.
The two magnetic tape recorders are shown in the background of
Fig. A.1.5-1. The two small preamplifier units and the three
transceivers in the foreground of the photograph are discussed
in Section A.2.
A.1.6 Calibration of Instrumentation
The electrical calibration of all instrumentation was tested very
extensively in the laboratory prior to the first quarry blast
measurements to determine all the important features required to
successfully record and analyze the noise and vibration phenomena.
a
f'i
¦j
il
u
y
y
y
A-10
u
-------
Outdoor
Measurements
Ground Velocity
Dynamic Range
Freq. Range
L
0.00003 - 0.03 m/sec
4-1000 Hz
1
<
SPL
V
a
70-130 dB
Indoor Measurements
SPL
SPL
VEL
^CCEL
VEL
VEL
a
a
70-130 dB
70-130 dB
0.00003 - 0.03 m/sec
0.001-1 g
0.00003 - 0.03 m/sec
Vert, or Horiz.
0.00003 - 0.03 m/sec
Vert. (V)
SPL
f~\— SLM
A-wt.
0.1-2500 Hz
0.1-2500 Hz
0.5-2500 Hz
4-1000 Hz
0.5-2500 Hz
Mic
1C O"
Talk
><»
8 channel 1—^ V
FM tape
recorder
0-2500 Hz
dynamic range:
50 dB broadband
60 dB in freq.
range of
interest
" '0
o
0>(>
Fig. A.1.5-2.
Blast Noise and Vibration Field
Recording System Used Early in
the Measurement Program
A-ll
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The tests included frequency response, phase response, dynamic
range as a function of frequency, gain stability, and dc drift.
The transducers illustrated in Fig. A.1.4-1 were calibrated
periodically in the laboratory. The sound-measuring instruments
were calibrated in the field with the appropriate acoustic calibra-
tors shown in the photograph. Dynamic calibration of the velocity
transducers proved to be the most difficult. A.medium-force
electromagnetic shaker system would have been desirable, but was
not available. A satisfactory substitute calibrator was made by
modifying a heavy-duty magnetic solenoid, shown between the two
seismic cages in Fig. A.1.4-1. The solenoid was supported by
a large bench vise to provide either vertical or horizontal motion
as required by the individual velocity pickups. A small accelerom-
eter (with calibration traceable to NBS) was attached to the end
of the velocity pickup. The voltage to the solenoid was carefully
adjusted to provide 1 g excitation of the velocity pickup. The
60 Hz power line was used to drive the solenoid (electromagnetic
shaker) and a narrow-band spectrum analyzer was used to accurately
measure the output voltage of each pickup at 120 Hz. The pickup
was excited at 1 g, at 120 Hz. The velocity pickups were found
to be extremely stable in their sensitivity and all produced the
same output signal within +0.25 dB.
A.1.7 Signal Cables and Connectors
Experience has shown that defective cables or connectors are the
most common problems encountered in field measurements that require
A-12
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quality recordings of sound and vibration phenomena. To minimize
such troublesome problems, all signal cables consisted of coaxial
cable (RG-58C/U) meeting military specifications and BNC connectors
and BNC hardware and adaptors. To check the signal cables in the
field, a 1-volt square wave signal, first at 10 Hz and then at
100 Hz, was injected at the transducer end of the cable and1
monitored (at the other end of the cable) at the tape recorder
with an oscilloscope to assure that the cable was performing as
expected. The FM tape recorder electronics was also included in
this electrical square wave test loop. This made it possible to
quickly assess the frequency response and gain and proper func-
tioning of the entire system short of the transducer. A square
wave test signal was chosen to quickly check both the low and high
frequency gain characteristics simultaneously for each transducer
channel.
A.2 Blast Noise and Vibration Recording Systems
This section will discuss how the equipment described in the
previous section was utilized on a typical field trip to measure
a quarry blast. Mr. Greg Zak of Illinois EPA (IEPA) obtained
blast noise recordings simultaneously with the recordings of
Kamperman Associates Inc. The IEPA recordings were made much
closer to the blast event (on the quarry property) in an attempt
to gain additional data for scaling the blast noise as a function
of distance and weather conditions. A brief discussion follows
of the various instrumentation systems used in the 1975 Illinois
A-13
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IEQ blast noise study. This section concludes with a description
of the alterations made this year to the mobile system to improve
the signal-to-noise ratio of the recorded signals.
A.2.1 The Mobile Recording System
The sound- and vibration-measuring transducers and recording
instrumentation are shown in Figs. A.1.4-1 and A.1.5-1. The
interconnection of these components ir> outlined in the block
diagram of A.1.5-2. A small temporary bench placed upon the rear
seat of a sedan supported the instrumentation shown in Fig. A.1.5
Time to respond to the announcement of a quarry blast was neces-
sarily very short. From August 23 to the middle of October, 1976
personnel from Kamperman Associates Inc. were in daily contact
with two or more of the five participating quarries in the
Chicago area. The wind direction and the blasting schedule of
a particular quarry, and the quarry's ability to locate a home
to be instrumented downwind of the blast, determined whether or
not one would be able to obtain an air blast measurement. It was
agreed at the outset of the program that the quarry operators
would be responsible for locating typical dwelling next to their
quarry where measurements could be taken. To avoid any complica-
tions with neighbors, quarry operators agreed to restrict our
measurements to the homes of quarry employees or close friends.
A further requirement was that a member of the household must be
at home at the time of the blast measurement. This combination
of requirements made the measurement options very limited.
A-14
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After receiving a go-ahead signal from a quarry that was preparing
a blast and had located a home downwind of the blast, the team
required approximately 10 minutes to connect up the instrumentation
in an auto, an additional half-hour to arrive at the selected home,
and 20 minutes more to set up recording instruments inside and
outside the home. Sometimes the wind would change direction
during the one-hour period before the blast, and the recorded
blast would be crosswind rather than downwind of the blast.
The vibration transducers were attached to a concrete driveway
or sidewalk outside the dwelling. Modelling clay was found
adequate to securely attach the three component velocity gauges
to the concrete. Several years ago, personnel from Kamperman
Associates Inc. carried out carefully controlled experiments to
determine the "best" method for measuring ground vibration. The
best method is obtained by placing the vibration pickup securely
on top of a 1-foot diameter previously poured concrete column
that extends vertically 5 to 10 feet into the ground. The
second-best choice is to bury the vibration pickups in the
ground and firmly compact the soil after burial. However, this
procedure has many drawbacks. It can prove very difficult to
maintain proper orientation of the pickups while compacting the
soil. Ground water and moisture are often a serious hazard.
Digging a hole in the ground to bury vibration pickups can also
be quite a chore, especially if the ground is frozen. For these
reasons, the simplest choice is to place and secure the pickups
A-15
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onto a hard exposed level surface. This can and does produce
almost as good results as could be obtained by placing the pickup
on the specially poured and buried concrete column. The surface-
mounted monitoring procedure is by far the easiest, and if one
avoids utilizing concrete slabs that do not make firm contact
with compacted earth, the measured results are usually within 1 or
2 dB or those made on the buried concrete column. A typical
concrete roadway will show a slight resonance of around 60 Hz.
Inside the dwelling, the velocity pickups or accelerometer were
generally mounted in the center of the floor, unless there was a
major supporting beam immediately under the center. The floor
surfaces consisted of a variety of constructions, including poured
concrete slab on grade, poured concrete slab with a basement under-
neath, and, on the second floor of a large concrete block building,
precast and prestressed concrete planks finished with poured
concrete on top of them. One blast measurement was made on each
of these constructions. All other measurements were made on a
variety of wood frame constructions on the first or second floor
of homes containing basements. The majority of the floor con-
structions consisted of standard oak flooring nailed to a wood
subflooring. Some of the newer homes had plywood subflooring and
a finished surface,of hardwood, cemented vinyl tile, or cemented
ceramic tile. After the transducers were secured to the floor
surface, they were pulled on to assure that there was good contact
between the transducer and the floor surface, and that the floor
A-16
-------
surface was securely attached to the subflooring. Occasionally
wall-to-wall carpeting was encountered and required a different
transducer-mounting procedure. The seismic cage containing the
three velocity transducers was not used when carpeting was en-
countered. For the carpet situation, the transducers were removed
from the seismic cage, placed directly on the carpet, and held in
position with heavy weights, such as the 25-pound bag of lead shot
shown in Fig. A.1.4-1.
The measurement of wall Vibration as well as floor vibration during
a blast event was considered early in the project. It was con-
cluded that, with the limited resources available, the study
should concentrate on the floor vibration. Although walls do
vibrate from the ground wave and air blast, which may also rattle
windows, dislocate bric-a-brac sitting on wall shelves, and
transmit vibratory energy into the floor, it is the floor that
ultimately shakes the occupants of the dwelling, and for this
reason the vibration of the floor was considered the principal
subject of interest for this study.
The outdoor sound-recording microphone was supported approximately
1-1/2 meters above the ground with a tripod, and located approxi-
mately 10 meters from the side of the dwelling. The microphone
was positioned to receive the blast wave in much the same way
that the dwelling would receive it, and at the same time to avoid
blast noise reflection from the dwelling back to the microphone.
A-17
-------
The indoor microphones were positioned on tripods and. located
in the rooms containing the floor vibration pickups. All micro-
phones were covered with Bruel & Kjaer windscreens. The wind-
screens on the indoor microphones served only as physical protectors
for the microphones.
Several redundant electrical field calibrations were performed
before and after each blast event. The sound-measuring systems
were checked with the appropriate acoustic calibrators. Field
calibration of the vibration transducers could not conveniently be
done. The operation of the vibration pickups was monitored on an
oscilloscope before and after each blast by noting the signal
from each pickup as a person walked across the floor inside the
dwelling or on the concrete slab containing the outdoor vibration
pickups outside the dwelling. Stable electrical calibration
signals available from the data tape recorder plus the external
portable square wave generator permitted accurate gain adjustment
over a 26 dB range of 0.5 volts to 10 volts full-scale input
voltage to the tape recorder.
Changing weather conditions have no known influence on the ground-
borne vibration from a quarry blast. However, local weather con-
ditions, and particularly the wind, strongly influenced the
magnitude of the air blast received at the dwellings studied.
The wind direction was noted at the time of the blast and the
wind velocity was measured with the small hand-held gauge shown
A-18
-------
in Fig. A.1.4-1 located just to the left of the acoustic calibra-
tors in the foreground of the photograph. The cloud cover and
air temperature were also recorded. The wind velocity at the
edge of the quarry where the portable blast noise recorder was
located always produced higher values because of the lack of
obstructions such as existed in the residential area. The wind
velocity measured at the edge of the quarry is reported with
each blast event.
Reliable radio communication between the quarry blasting crew,
the portable blast-noise-recording operator, and the operator
of the mobile recording system at the instrumented dwelling
proved to be essential. CB transceivers were initially used for
this purpose in the 1975 Illinois IEQ blast noise study. However,
it was soon discovered that all available frequency bands were so
heavily utilized that it was sometimes difficult to coordinate
the recording with the blast event. To circumvent the problem
in the 1975 study, three transceivers operating at licensed
commercial frequencies of around 150 megahertz were utilized.
These hand-held transceivers are shown in the bottom right corner
of Fig. A.1.5-1.
A.2.2 Portable Blast Noise Recorder
Mr. Greg Zak of the Illinois EPA assisted Kamperman Associates Inc.
throughout the program. It was his objective to record the air
blast simultaneously with the recordings being made by Kamperman
A-19
-------
Associates Inc. (located at a more distant dwelling). The portable
recorder was set up 100 to 500 meters from the actual blast. The
portable recorder was always located within the property of the
quarry.
A block diagram of the portable recording system is shown in Fig.
A.2.2-1. A GenRad type 1971 ceramic microphone was connected to
a GenRad type 1933 preamplifier. The output signal from the pre-
amplifier was fed directly into the FM channel of a Nagra type SJ
tape recorder. No gain controls or preamplifiers (except the
microphone preamplifier) were used for the portable system. The
low-frequency response of the microphone and preamp system was
determined by very carefully inserting the microphone into a
Bruel & Kjaer type 4 220 pistonphone acoustic calibrator and
observing the frequency spectrum that was produced when the cali-
brator was turned off and the pistonphone was allowed to coast to
a halt. The same experiment was repeated utilizing the Bruel &
Kjaer carrier microphone system with a known cutoff frequency of
0.1 Hz. By comparing the spectra captured on a real-time analyzer
of the Bruel & Kjaer carrier system with the ceramic microphone
and preamp system, the 3 dB down point could be determined for
the ceramic microphone and preamp combination.
The measurement procedure utilized in the field was simple. The
microphone and its associated preamplifier were supported approxi-
mately 1.5 meters above the ground with a tripod. An acoustic
A-20
-------
2.5 cm
(1 inch)
ceramic
mic
a
0 dB
80-145 dB SPL,
0.6-2000 Hz
pre
amp
tape recorder
FM + direct
Nagra SJ
a
Talk mic
Fig. A.2.2-1.
Portable Air Blast Recording System Used by Illinois EPA
Personnel for the 1975 IEQ and 1976 EPA Quarry Blast Noise
Study
A-21
-------
calibration tone of 114 dB was applied to the microphone with
a GenRad type 1562 calibrator. The calibration signal was
recorded on the magnetic tape recorder prior to each blast.
In addition to recording the quarry blasts in the Chicago area
together with Kamperman Associates Inc., Mr. Zak was able to
supplement this data with blast measurements at two silica sand
quarries and a down-state limestone quarry, and three blast
measurements at an open pit coal mine. All the measurements
recorded by Mr. Zak have been analyzed, and the results incor-
porated into this report.
A.2.3 Recording Systems Used in Illinois 1975 IEQ Blast Noise Study
The most significant support for the IEQ blast noise study was
provided by the Bureau of Mines at Twin Cities Mining Research
Center under the direction of David Siskind. The Bureau of Mines
provided the IEQ blast noise study with a van containing noise-
and vibration-measuring and recording instrumentation plus staff
to operate the equipment. A description of their instrumentation
will be published in the spring of 1977."'"''' Greg Zak of the
Illinois EPA office in Springfield provided support to this EPA
blast noise study similar to that he gave in 1975 to the Illinois
IEQ study. The instrumentation system used by Greg Zak for both
programs is shown in Fig. A.2.2-1. Kamperman Associates Inc.
utilized a blast-noise-measuring system similar to that used by
IEPA in 1975, A simplified block diagram of the recording system
A-22
-------
is shown in Fig. A.2.3-1. In addition to the tape-recorded
information obtained by the three groups, each group used a GenRad
1933 sound-level meter set for C-weighting and slow meter response
to obtain direct readings during a blast. Kamperman Associates Inc.
also used a modified GenRad 1981 to read the C-weighted slow
response of the air blast events for both studies. The modified
GenRad 1981 had the advantage of reading out in digital form the
maximum level reached (C-weight, slow response) in each blast,
which was preferable to depending on the observer's ability to
read a fast moving meter at the time the blast wave passed.
All blast recordings made by IEPA and Kamperman Associates Inc.
on the 1975 IEQ study were analyzed with the system shown in
Fig. A.2.3-1. The 500-line real-time frequency analyzer and
the X-Y plotter were loaned to Kamperman Associates Inc. by the
Bureau of Mines. The analyzer was a Nicolet Scientific Corp.
model 500A. This is a time-compression-type analyzer with a
Hanning window. The test results obtained from the analysis of
the IEQ blast noise study have been reanalyzed with the 1976
data analysis system, designed for the EPA study, and are
incorporated into the results of this report. The test results
obtained by the Bureau of Mines during the IEQ blast noise study
was recently published by the Bureau.^ Data from their report is
also incorporated into the summaries contained in this report.
A.2.4 Alterations to the 1976 Mobile Recording System
For the IEQ blast noise study of 1975, the Bureau of Mines made
A-23
-------
2.5 cm
Laboratory Blast Noj se Analysis System
Fig. A.2.3-1. Blast Noise Recording and Analysis System Used by
Kamperman Associates Inc. for 1975 IEQ Study
A-24
-------
all the vibration measurements. The results of their measurements
are summarized in Ref. 3. These data show less of a decrease in
ground vibration level with distance than was found on the quarries
measured in the EPA study. The Bureau of Mines results from the
IEQ study were the basis for establishing the vibration-measuring
sensitivity requirements for the EPA study. It came as a surprise
last fall to find that the quarries in the Chicago area produced
less ground vibration. The ground vibration levels were lower
than expected for a number of reasons. The charge weight per delay
was, on the average, less last fall than that measured in 1975.
Furthermore, the distance between the blast event and the instru-
mented dwelling was increased far more than had been anticipated
(1000 meters) in order to separate the arrival time of the ground
wave from the arrival of the airborne blast wave at the instrumented
dwelling. To overcome these lower signal levels, 30 dB preampli-
fiers were quickly constructed and inserted in the signal leads
from each velocity transducer. An additional preamplifier was
constructed for the acceleration measurements that permitted a
gain increase up to 40 dB in 10 dB steps.
The added preamplifiers are illustrated in Fig. A.2.4-1 in block
diagram form and are shown in the foreground of the center of the
photograph in Fig. A.1.5-1. In the early phase of the measurement
program during the current study, two rooms were instrumented
simultaneously in a dwelling. The sound level and the vertical
velocity of the floor in the two rooms were recorded during the
A-25
-------
blast. It was believed that the vertical component in the floor
would be the most significant motion during a blast. However,
to prove this, it was decided that the three mutually perpendicular
planes (lateral, transverse, and vertical) should be measured
simultaneously. The limited number of available data-recording
channels permitted the recording of sound and vibration in one
room only during a blast event.
No additional technical problems were encountered during the field
measurement phase of this program. The total number of recorded
blast events was strictly dictated by the number of homes (18)
located downwind of a quarry blast that were available for measure-
ment.
A.3 Analysis of Recorded Blast Noise and Vibration
Immediately after the recording of each blast, the instrumentation
was returned to the laboratory for analysis of the recorded signals.
The storage oscilloscope was used in the field to check the con-
dition of the recorded signals immediately after a blast if a
second blast was to follow within an hour or two.
A.3.1 Data Analysis Systems
A wide variety of signal analyses was performed by the instrumenta-
tion shown in Fig. A.3.1-1. The data analysis methodology is
described in the following subsections.
A-26
-------
Outdoor Measurements
Ground Velocity
L
~"if
<~
Dynamic Range
000001 - 0.01 m/sec
SPL
V
Q
70-130 dB
Indoor Measurements
SPL
ACCEL
0-5
70-130 dB
0001-1 g
Floor Velocity
0.000001 - 0.01 m/sec
<1
lS
V
SPL
O—A-
SLM
•wt.
40-80 dBA
Mic
ioO-
Talk
Mic
Fig. A.2.4-1.
Blast Noise and Vibration Field
Recording System Used for the
Major Portion of the Measurement
Program
-0
1
8-channel
FM tape
recorder
0-2500 Hz
dynamic range:
50 dB broadband,
60 dB in freq.
range of
interest
©
—1> <>
—E> o
T
—()
—^ <)
—£> o
—{> i
{> ^
storage
scope
DVM
A-27
-------
' ' j|
. % W
Fig. A.3.1-1 Data analysis instrumentation.
A. 3 . 2 Time History of Blast Event
The sound and vibration data recorded on the Hewlett Packard type
3968A eight-channel tape recorder was first reproduced into an
eight-channel oscillograph chart recorder (Honeywell Visicorder
Model 1858). The setup for the time history analysis is shown
in Fig. A.3.2-1. The FFT analyzer (Nicolet Scientific Corp. Model
44OA) was utilized in the time domain to locate the blast event
on the magnetic tape. The photosensitive strip charge is 0.2
meters wide (8 inches) and was normally operated at a chart speed
of 0.1 meters per second. The blast event extended over a period
of 5 to 8 seconds and thus some of the chart records are approxi-
mately 1 meter long. In order to present this information in this
report, additional records were made with a more compressed time
\
A-2 8
-------
8-channel
field tape
recorder
0-2500 Hz
4
FFT analyzer
used in time
domain for
locating blast
on tape
8-channel
oscillograph
chart
recorder
0-2500 Hz
Chart
Fig. A,3.2-1. Simultaneous Time History Analysis of Eight Noise and Vibration
Signals Recorded During a Single Blast Event
A-29
-------
scale. The photo-sensitive record was then photographed and
reduced 20% and placed in Appendix B. A detailed discussion
of a typical record of blast noise and vibration amplitude is
covered in Section A.4.
A.3.3 Spectrum Analysis and Frequency Weighting
A detailed spectrum analysis was made of a recorded noise and
vibration signal associated with a particular blast event. The
transducers located outside a dwelling recorded only one signal
of interest; either the air blast or the ground vibration. The
transducers inside the dwelling recorded two signals. The first
signal was the noise and vibration in the house caused by the
ground-borne vibration from the blast, and the second signal was
the noise and vibration in the house caused by the air blast. A
separate analysis was made of each of these signals.
The fast Fourier transform (FFT) spectrum analyzer provided a
detailed spectrum of each signal. The spectrum was then plotted
on graph paper with the aid of a Hewlett Packard type 7045A X-Y
recorder as shown in Fig. A.3.3-1.
The spectrum analysis of an impulse or shock, such as that associated
with blast noise, is best accomplished with a true FFT analyzer.
It is also important that the impulse signal be stored unweighted
in the time domain. A rectangular "window" should be used for
analyzing impulses. This program is illustrated in Figs. A.3.3-2,
A-30
-------
Fig. A.3.3-1. Data Analysis System for Determining Blast Noise and Vibration
Spectrum, Peak and Various Sound-Level Meter Descriptors
A-31
-------
y
Fig. A.3.3-2 Amplitude—time history
of an air blast.
Pig. A.3.3-3 Air blast frequency
spectrum with rectangular "window."
A.3.3-3, and A.3.3-4. A 4-
second-long air blast signal
is shown in the photograph in
Fig. A.3.3-2. This photograph
was taken of the FFT display in
the time domain for a typical
blast. The same signal is then
shown in the frequency domain in
Figs. A.3.3-3 and A.3.3-4. The
only difference between the
settings on the FFT analyzer
for Figs. A.3.3-3 and A.3.3-4
is the position of the weighting
or "windowing" switch. The
spectrum shown in Fig. A.3.3-3
was obtained with a rectangular
window (no weighting) and the
spectrum in A.3.3-4 was obtained
with a Banning weighting of
the data displayed in Fig.
A.3.3-2. The frequency range
in Figs. A.3.3-3 and A.3.3-4
is 0 to 100 Hz full-scale with
10 Hz intervals marked along
the top and bottom of the fre-
quency (F) scale. The decibel
a
y
y
y
y
y
ii
A-32
-------
scale (DB) on the left is
60 dB full-scale and 10 dB per
division. The difference in
the spectra shown in Figs.
A.3.3-3 and A.3.3-4 illustrates
the magnitude of the error
encountered in Fig. A.3.3-4
by utilizing the Hanning or
cosine squared weighting on
the blast signal shown in Fig.
A.3.3-2. There is a peak in
the spectrum at 18 Hz in Fig. A.3.3-3, which is suppressed about
15 dB in Fig. A.3.3-4. Many real-time spectrum analyzers which
were on the market prior to the introduction of the FFT analyzer
contain Hanning weighting only and thus are subject to the errors
discussed here. This error with a Hanning window can be reduced
to one dB or less if the entire signal of interest is positioned
in the center half of the time storage (or window).
The detailed spectrum analysis of each quarry blast noise and
vibration signal recorded was automatically plotted on a large
sheet of graph paper.
Whenever the signal-to-noise ratio of the recorded signal was
particularly poor, an additional spectrum analysis of the back-
Fig. A.3.3-4 Air blast frequency
spectrum with Hanning "window."
A-3 3
-------
ground noise just prior to the blast event was also analyzed and
plotted to permit one to separate out the "wow" and "flutter"
components of the tape recorder from the true noise and vibration
signal of interest. Faithfully recording the entire frequency
spectra of quarry blast events requires a data-recording and
reproduction system with outstanding dynamic range. The eight-
channel FM tape recorder had a 50 dB dynamic range over the total
bandwidth from 0 to 2500 Hz when recording and reproducing at a
tape speed of 19 cm/second (7.5 ips). In the primary frequency
range of interst (0 to 200 Hz) the dynamic range of the tape recorder
was 60 dB. This dynamic range was set by the fundamental frequency
of the wow and flutter component (near 6 Hz). All harmonics of
the wow and flutter component were more than 70 dB down. The tape
recorder had a harmonic distortion level of less than 0.3% at full
record level. The portable cassette data recorder shown in Fig.
A.3.3-1 was utilized to record the A-weighted sound level inside
a dwelling during a blast. The broadband dynamic range of this
recorder was approximately 4 5 dB with a maximum harmonic distortion
level of 1%.
Many different analyses were attempted utilizing the standard
type 1 (precision) sound-level meter with different weighting
networks or external filter networks. The adjustable high-pass,
low-pass filter was a Kron-Hite model 3322. The roll-off
characteristics outside the band pass for this filter is 24 dB
per octave. The sound-level meter shown in the block diagram in
A-34
-------
Fig. A.3.3-1 was a GenRad type 1933. This instrument was some-
times replaced by a GenRad type 1981 that had been modified for
C-weighting. The modified instrument had the advantage of being
able to capture the maximum signal level and display it continuously
in digital form. The frequency spectra of all data for this study
is available at EPA/ONAC. Comparisons of various descriptors
are summarized in several tables contained in Section 3.4
A.3.4 Determination of the Noise and Vibration Energy (VEL) from
a Blast Event
The system assembled for determining the energy density (VEL and
SEL) using various filtering devices is shown in Fig. A.3.4-1.
The oscilloscope and the FFT analyzer served primarily to locate
the portion of the blast event that was to be analyzed (separating
the indoor noise and vibration from the ground wave and the air
wave produced by a quarry blast). The oscilloscope was used
primarily to assure that the DC offset in the signal entering
the squaring device was at or near 0 volts DC immediately prior
to the arrival of the blast signal. The squaring and integrator
was a DC pass system and thus it was most important to avoid any
undesirable DC offset into the detector system, since this would
lead to errors in the final answer. The squaring device was made
up of analog computing modules. The integrator was a classical
Miller integrator with a selectable time constant of 1 second or
10 seconds. The output of the integrator was fed directly to a
A-35
-------
8-channel
field tape
recorder
0-2500 Hz
cassette
recorder
25-10 K Hz
adjustable
HP, LP
filter,
C-wt, A-wt,
5.6 Hz LP
—o
Fig. A.3.4-1. Data Analysis System for Determining Blast Noise and Vibration
Energy, SEL and VEL.
A-36
-------
conventional DC digital voltmeter. Initially a log converter
was placed between the integrator and the digital voltmeter so
that the digital voltmeter would read directly in decibels.
However, the small but important DC drift in the output of the
logging device created unacceptable errors in the digital volt-
meter readout. With the removal of the log unit, the voltmeter
reading was converted back into decibels by simply computing the
log of the signal with a hand calculator.
To calibrate the SEL/VEL meter, a reference tone from the tape
recorder was played through the system and the signal was integrated
for exactly 10 seconds with the integrator switch in the 10-second
position. The output answer then became the reference for the
1-second position on the integrator. In this way all impulse
signals, irrespective of their duration, were automatically
normalized to 1-second integration time.
Determining the SEL/VEL of the various signals placed the most
stringent requirements on the dynamic range and DC drift of the
tape recorder. Initially it appeared desirable to compute the
vector sum of the vibration signals from the three mutually per-
pendicular velocity pickups. The idea was fine, but it proved
almost impossible to execute accurately. To enhance the usable
dynamic range of the tape recorder by 10 dB, three identical 4-
pole (24 dB per octave) low-pass filters set at 200 Hz were inserted
in the three signal lines from the tape recorder to the vector-
A-37
-------
summing device. The low-pass filters helped the situation, but
there were two remaining problems that finally discouraged the
use of the vector-summing device. It has been pointed out how
important it is to maintain a near zero offset voltage (immediately
prior to the blast signal) when entering the squaring device and
integrator. This problem exists for a signal entering the vector-
summing device, except now one must maintain zero offset for three
signals instead of just one. This proved to be a problem for
signals with a fair to poor signal-to-noise ratio. The second
problem had to do with the primary wow and flutter component from
the tape recorder. The vector-summing device saw this frequency
component arrive in phase from all three channels simultaneously
and thus it squared the undesirable wow signal and summed all
three signals in phase. It was finally concluded that the most
accurate value for the vector sum would be arrived at by mathe-
matically summing the output signal from the digital voltmeter for
the three individual components analyzed separately. In situations
where the signal-to-noise ratio was particularly poor, the SEL/VEL
would be determined for the particular blast event; a section of
the tape immediately before the blast would be analyzed for pre-
cisely the same amount of time, and the resultant answer on the
digital voltmeter subtracted from the results obtained during tJie
blast. Whenever the output voltage from the integrator was not
at least twice the value of the background noise, the results were
not reported. Fortunately, this 3 dB signal-to-noise ratio
situation was seldom encountered.
A-38
-------
The results of the SEL/VEL analysis of all recorded signals
utilizing a variety of input filters and weighting networks is
contained in Table A.4.3-2. Comparison of the SEL/VEL results
with other descriptors is summarized in Section 3.4.
The peak values for the lateral, transverse, and vertical vector
sums were difficult to obtain accurately from the tape-recorded
signals for the reasons just discussed. This loss of information
is not considered significant since the peak vector sum is normally
equal to the maximum peak of any one of the three components.
The C-weighted SEL air blast data was difficult to obtain outdoors
because the measuring microphone was also required to measure the
1 Hz air blast peak, which was found to be typically more than
25 dB above the C-weighted SEL.
A.4 Data Presentation and Interpretation
A.4.1 Time History Records
The time history of the blast shows the separation of the ground-
borne wave outside to the airborne wave outside and the effect
each one has on the inside of the dwelling. Figure A.4.1-1 is
a sample oscilloscope recording of blast 15 displaying the lateral,
transverse, and vertical velocity measurements outside (channels 1,
2, and 3, respectively); the airborne wave outside (channel 4);
the vertical floor acceleration inside (channel 5); and the lateral,
transverse, and vertical floor velocity inside (channels 6, 7, and 8,
A-39
-------
>
I
Outdoor
Lateral
Veloci ty
Outdoor
Transverse
Veloci ty
Outdoor
Vertical
Veloci ty
Outdoor
Sound
Pressure
Vertical
^ Flnnr
O 1 • -
Acceleration
Lateral
Floor
Velocity
Transverse
¦s. F1oor
o Velocity
—i
Vertical
^ Floor
o Velocity
o
<=
o
CO
Fig. A.4.1-1. Oscillograph Record of Blast No. 15
-------
respectively. All eight traces were made simultaneously, with
the vertical lines representing one-second time intervals. No
absolute amplitude scale was intended for these oscillograph
records, only the time history. However, the three outdoor velocity
traces (1, 2 and 3) have twice the signal amplification of the in-
door velocity traces (6, 7 and 8). This time history shows the
arrival of the ground-borne wave outside and the resultant vibra-
tion inside the house. This signal decays until the airborne wave
arrives and initiates a second vibration inside the house. Figure
A.4.1-2 is an oscillograph recording of blast 7 displaying the
lateral velocity outside (channel 1), the outdoor airborne wave
(channel 4), and the indoor sound pressure (channel 5). This time
history shows the arrival of the ground-borne wave outside and the
resultant noise inside due to the vibration of the house and pos-
sibly the rattling of bric-a-brac. The airborne wave arrives
later and passes into the house nearly unchanged. The walls of
the home filter out the high-frequency content of the sound wave
but are transparent to the low-frequency (approximately 1 Hz)
component. Therefore, the overall shape of the time trace of the
indoor sound pressure is identical to that of the outdoor sound
pressure, but the jaggedness due to the higher frequencies present
in the outdoor trace is absent from the indoor trace. Oscillo-
graph records of blast 1 through 18 are included in Appendix B.
The most important information given by the oscillograph records
is the time history, which permits correlation between the outdoor
A-41
-------
>
I
¦U
to
Outdoor
Lateral
Velocity
Outdoor
Sound
Pressure
Indoor
Sound
Pressure
"O
PO
O
o
o
oo
a a
ru UJ
j+-1 sec ->|
Fig. A.4.1-2. Oscillograph Record of Blast No. 7
-------
signal and the resultant indoor signals. By examining the
oscillograph records, a sharp line could be drawn in most cases
between the indoor sound and vibration caused by the ground wave
and the indoor sound and vibration caused by the air wave. It
was surprising to find that the ground vibration measured outside
the dwelling caused the dwelling walls and floors to vibrate for
a longer period than the signal duration in the ground outside.
The same phenomenon happens with the blast wave, but it is not as
obvious from the oscillograph records. It has been pointed out
elsewhere in this report that it is necessary to separate,the
blast site from the dwelling to be monitored by a distance of
about 1000 meters in order to have a clear separation of the signals
produced by the ground wave and the air blast. At these great dis-
tances the signals were very low, and sometimes interference from
footfalls and other activity in the dwelling caused unwanted signals
close to the blast events of interest. The oscillograph records
were of great assistance in determining the exact time for signal
analysis, and thereby eliminating unwanted sound and vibration
signals during the blast. A few oscillograph records showed ground
waves arriving at different times due to different paths in the
earth (see blasts 7, 15, and 18). Monitoring the indoor vibration
in a typical dwelling within 300 meters of a blast event made it
impossible to separate the contributions of ground-borne energy
and the airborne blast wave. When the distance between the blast
event and the instrumented dwelling was increased, the oscillograph
records made the relative importance of the ground and air waves
more apparent.
A-43
-------
A.4.2 Frequency Spectra
Frequency spectra of selected signals from blast 15 are shown in
Figs. A.4.2-1 through A.4.2-9. There is no absolute full scale
for these spectra although they are accurately marked in 10 dB
,("DB" on left side of figures)
increments with a total range
of 60 dB. The absolute magni-
tude of these spectra was
determined by automatically
plotting the detailed spectra
on large graph paper. The fre-
quency range noted by "F"
along the bottom of the spectra
is linear from 0 to 200 Hz
Fig. A.4.2-1 Outdoor lateral ground
velocity for blast no. 15. for all. The frequency spectra
of the outdoor lateral and
vertical ground velocities
Fig. A.4.2-2 Outdoor vertical ground
velocity for blast no. 15.
Fig. A.4.2-3 is a frequency
spectrum of the outdoor sound
pressure. These three spectra
demonstrate that the ground
wave contains the major portion
of its energy between 5 and 100
A-44
-------
Hz. The frequency spectra of the indoor lateral floor velocity
due to the ground-borne wave and airborne wave are shown in Figs.
A.4.2-4 and A.4.2-5, respectively. These two spectra demonstrate
that the frequency content of the outdoor ground-borne and airborne
waves is transferred into the
dwelling vibration. Both
spectra show a prominent
frequency component at 8 Hz,
even though this frequency com-
ponent is not of major importance
in the outdoor ground velocity
or sound pressure. This fre-
quency component is probably
the resonant frequency of the
floor in this horizontal
direction. Figures A.4.2-6
and A.4.2-7 are frequency
spectra of the vertical floor
velocity due to the ground-
borne wave and the airborne
wave, respectively. These
spectra also show higher fre-
quency content due to the
ground-borne wave than to the
airborne wave. To ensure that
there are no frequency com-
ponents of the ground-borne
Fig. A.4.2-3 Outdoor sound pressure.
Fig. A.4.2-4 Indoor lateral floor
velocity due to the ground wave.
A-45
-------
wave or airborne wave below the 4 Hz cutoff of the velocity trans-
ducers, the acceleration frequency spectra of the vertical floor
vibration due to the ground-borne and airborne waves were analyzed.
These spectra are shown in Figs. A.4.2-8 and A.4.2-9. The ground-
borne wave contains no
significant energy below 5 Hz
in the acceleration spectrum.
The acceleration of the floor
due to the airborne wave does
show a frequency component at
1 Hz, but this component is
of little significance compared
to the energy between 10 and
50 Hz.
Fig. A.4.2-5 Indoor lateral floor
velocity due to the air wave.
Some spectra show a relatively
high level component near 0 Hz.
This very low frequency informa-
tion is caused by low-frequency
(DC) drifting in the total
record-re produce system and
should be ignored when viewing
the spectra.
Fig. A.4.2-6 Indoor vertical floor
velocity due to the ground wave.
The frequency spectrum obtained
with the FFT narrowband analyzer
was examined in detail for each
A-46
-------
signal from all recorded blast events. A careful study of all
of the outdoor gound velocity spectra showed that the bandwidth
of ground vibration was encompassed between 5 and 200 Hz. The
spectra from the air wave had a very prominent component at 1 Hz
(+ 0.5 Hz) and a very sharp
roll-off above and below this
frequency. Examination of
the indoor blast noise and
vibration spectra showed
energy at the same frequencies
found outside. A vibration
criterion was established for
a typical dwelling by deter-
mining the frequency bandwidth
at which the indoor floor
velocity signal levels were
higher than the ground velocity
measured outside the same
dwelling. A composite of all
of the data suggests that the
principal range of interest is
from 5 to 50 Hz, with secondary
resonances up to 200 Hz. This
vibration criterion formulated
Fig. A.4.2-8 Indoor vertical floor the basis for determining the
acceleration due to the ground wave.
transfer function utilizing
NOT REPRODUCIBLE
Fig. A.4.2-7 Indoor vertical floor
velocity due to the air wave.
A-47
-------
various descriptors with
different weighting or fre-
quency characteristics. The
air wave had to be treated in
a somewhat different fashion
because of the very prominent
1 Hz component. It was deter-
mined that the 1 Hz component
inside the dwelling was typi-
cally on the same level as the
1 Hz component outside the
dwelling. It was also found
that the 1 Hz component did not excite a typical dwelling at 1 Hz.
Therefore, a different criterion for evaluating the indoor vibration
caused by the outdoor air wave was established. This criterion
was specified as follows: Determine the peak level in the indoor
velocity measurement above 4 Hz and then determine the frequency
bandwidth at the 20 dB down points at either side of this peak
component. By comparing the various velocity spectra measured on
the floor of the dwelling, it was found that a frequency bandwidth
extending from 4 to 50 Hz would adequately describe the spectrum
required to correlate with the outdoor air wave. Inasmuch as this
data was obtained at a considerable distance (typically 1000 meters)
from the blast, it was considered important to extend the upper
frequency range to 200 Hz to encompass the higher frequency energies
that one would expect to find in a dwelling very close to a blast.
Fig. A.4.2-9 Indoor vertical floor
acceleration due to the air wave.
A-48
-------
Thus far the transfer function from the ground-borne wave to the
indoor floor vibration and the airborne wave to the indoor floor
vibration have been discussed. There are two additional transfer
functions that are of significance: the outdoor air wave versus
the indoor air wave or noise and the outdoor ground vibration that
causes noise inside the dwelling. The outdoor air wave entering
a typical dwelling is not attenuated at the peak frequency in the
vicinity of 1 Hz. This 1 Hz component is inaudible to humans.
The frequency range of principal interest would be the A-weighted
narrowband spectra. It was interesting to learn that the A-weighted
narrowband spectrum was nearly flat over the frequency range ex-
tending from 1 to 2000 Hz. In most instances the maximum energy
after the spectrum had been A-weighted coincided with the resonant
frequencies of the dwellings in the 10 to 200 Hz range. The A-
weighted recordings were made inside the dwellings during each
blast event to record the rattling effects from windows, bric-a-
brac on shelves, dishes in cupboards, and the dwelling in general.
These are all non-linear effects that are not readily scaled and
thus it is difficult to predict what the A-weighted sound level
will do with higher or lower air blast impingement upon the
dwelling.
To an observer standing outside a dwelling the passing of the
ground wave from a blast event appears very insignificant. The
measurement of the sound outside the dwelling confirms this. On
the other hand, the microphone signal inside the dwelling showed
A-49
-------
a substantial noise generated by the dwelling being shaken by the
ground wave. The prominent frequencies in the airborne spectrum
inside the dwelling were identical to the floor vibration fre-
quencies found in the dwelling. Part of the experiment was to
make limited measurements of the velocity of the walls during the
arrival of both the ground and air waves. From these measurements,
it was concluded that the floor velocity and the wall velocity were
very similar in magnitude and frequency. Both surfaces contributed
to the sound in the room and gave similar characteristics to the
sound spectra in the room during the passing of the ground wave.
A.4.3 Single-Number Descriptors
Section A.3 discussed in detail the data analysis procedures used
to determine a wide variety of single-number descriptors for each
of the blast measurements. The results of this analysis utilizing
the various descriptors are presented in Tables A.4.3-1 through
A.4.3-6. The maximum instantaneous peaks of each blast noise and
vibration signal shown in Table A.4.3-1 were determined from the
original calibrated oscillograph records that utilized an expanded
time scale to produce records approximately 1 meter in length.
These long and bulky records were easy to read but difficult to
reproduce in the report. The oscillograph records shown in
Appendix B are the same data presented in a compressed format.
All recorded data on blast noise and vibration were also passed
through a 4 to 200 Hz filter. The signal from the filter was
A-50
-------
Table
A.4.3-1 • Maximum instantaneous peaks of blast events (except acceleration weighted through a 5.6 Hz
low-pass filter from .5 Hz to 200 Hz). Data in dB re 1 m/sec for velocity, re 1 g for
acceleration and re 20 y pascals for sound pressure level.
Outdoor Ground
Velocity Outdoor
Lat. Trans. Vert. Sound
Blast re <3B re dB re dB re
No. m/sec m/sec m/sec 20 y pa
Indoor Sound
ground
dB re
20 y pa
air
dB re
20 y pa
Lateral
ground air
dB re dB re
m/sec m/sec
Transverse
ground air
dB re dB re
m/sec m/sec
Vertical
ground air
dB re dB re
m/sec m/sec
Vertical Floor
Acceleration
ground air
dB re dB re
1 g 1 g
1
-
-
-
-
87.0
106.5
-
-
-
-
-59.5
-
-52.2
-
2
-48.5
-49.5
-52.9
120.0
99.0
121.0
-
-
-
-
-49.1
-
-32.8
-51.1
3
-47.2
-46.3
-52.9
117.6
110.6
116.1
-
-
-
-
-45.0
-59.0
-46.1
-
4
-55.8
-52.5
-55.3
112.0
103.0
113.5
-
-
-
-
-51.0
-65.0
-41.4
-
5
-58.5
-61.3
-58.5
104.5
94.0
106.2
-56.9
-
-54.3
-
-56.7
-
-
-
6
-57.4
-57.8
-55.8
114.3
97.5
115.2
-58.1
-
-63.3
-
-55.4
-
-
-
7
-43.8
-42.7
-48.2
122.1
115.2
124.0
-40.1
-57.8
-46.9
-63.3
-40.8
-60.8
-
-
8
-69.1
-73.3
-73.3
112.2
-
113.0
-70.9
-77.0
-77.4
-77.4
-74.0
-64.9
-
-
9
-68.5
-69.8
-71.4
114.0
-
112.7
-68.0
-75.4
-68.5
-75.8
-63.7
-59.3
-
-
10
-70.2
-70.8
-69.7
111.9
86.6
115.5
-73.5
-68.8
-73.5
-77.7
-72.1
-63.7
-
-
11
-69.8
-72. 3
-68.2
113.6
84.7
114.4
-71.3
-70.3
-74.4
-79.4
-70.2
-74.4
-
-
12
-57.3
-63.1
-63.8
-
107.3
121.7
-62.8
-73.4
-
-
-52.4
-
-
-
13
-68.9
-63.3
-70.3
99.4
-
100.0
-62.9
-70.9
-57.6
-73.1
-61.7
-68.0
-
-
14
-75.4
-73.4
-74.9
123.8
-
-
-69.8
-76.9
-70.5
-72.1
-70.1
-76.9
-57.1
-56.8
15
-66.4
-65.8
-67.4
119.3
-
-
-63.8
-60.8
-65.3
-68.2
-60.5
-59.9
-49.4
-47.6
16
-64.5
-67.3
-67.7
115.9
-
-
-66.5
-81.3
-70.8
-79.8
-64.9
-68.0
-49.8
-53.7
17
-76.5
-73.7
-74.8
107.7
-
-
-74.6
-76.9
-71.6
-82.9
-74.6
-72.1
-61.1
-58.9
18
-72.0
-73.0
-76.9
116.8
-
-
-75.0
-70.3
-71.4
-71.7
-70.9
-70.6
-
-
>
I
-------
Table
A. 4.3-2-
The SEL and VEL results of blast events over a 4 Hz to 200 Hz filter (except accleration weighted
through a 5.6 Hz low pass filter from .5 Hz to 200 Hz). Data in dB re 1 m/sec for velocity,
re 1 g for acceleration and re 20 ypascals for sound pressure level.
Outdoor Ground Indoor Floor Velocity Vertical floor
Velocity Outdoor Indoor Sound Lateral Transverse Vertical Acceleration
Lat. Trans. Vert. Sound ground air ground air ground air ground air ground air
Blast dB re dB re dB re dB re dB re dB re dB re dB re dB re dB re dB re dB re dB re dB re
No. m/sec m/sec m/sec 20 y pa 20 y pa 20 y pa m/sec m/sec m/sec m/sec m/sec m/sec 1 g 1 g
1
-
-
-
-
79.8
88.0
-
-
-
-72.5
-75.0
-66.0
-
2
-61. 3
-61.0
-64.3
103.8
88.5
99.8
-
-
-
-62.1
-76.0
-44.2
-59.0
3
-62.4
-61.8
-70. 5
96.4
95.0
88.6
-
-
-
-61.6
-87.0
-57.3
_
4
-67.4
-65.0
-69.5
97.1
90.5
99.8
-
-
-
-61.5
-72.0
-50.2
-
5
-70.4
-71.0
-69.0
90.2
82.4
90.5
-67.7
-
-65.2
-67 .3
-
-
-
6
-68.4
-68.2
.-67.0
97.0
90.0
100.6
-67.6
-
-71.1
-65.2
-
-
-
7
-55.0
-58.1
-65.0
98.8
98.8
98.8
-50.6
-
-60.7
-56.6
-
-
-
8
-79.7
-85.9
-84.0
95.6
77.5
96.3
-84.0
-87.0
-87.0
-87.0
-80.0
-77.0
-
-
9
-77.5
-78.0
-80.0
97.8
76.2
98.9
-79.2
-84.0
-80.7
-78.5
-75.0
-74.0
-
-
10
-73.3
-75.0
-77.2
101.0
77.5
105.3
-77.2
-68.2
-79.6
-81.8
-74.4
-65.6
-
-
11
-78.0
-84.1
-81.5
97.9
72.8
101.0
-80.4
-76.4
-87.4
-88.0
-82.2
-83.4
-
-
12
-70.1
-75.7
-74.3
-
85.4
96.5
-74.1
-80.2
-
-
-66.4
-85.6
-
-
13
-75.6
-73.3
-78.0
89.4
75.0
91.0
-71.5
-
-66.7
-
-70.7
-78.2
-
-
14
-82.2
-82.2
-84.0
106.9
-78.5
-87.8
-78.5
-88.7
-78.2
-87.0
-66.0
-66.0
15
-77.0
-77.2
-78.0
102.4
-75.0
-67.2
-76.5
-95.0
-72.7
-69.9
-60.6
-56.5
16
-75.5
-78.5
-80.4
102.2
-79.5
-91.0
-82.1
-88.4
-78.2
-75.1
-66.0
-65.4
17
-85.0
-84.2
-86.6
92.0
-86.2
-87.0
-83.5
-92.5
-83.2
-80.6
-70.0
-69.0
18
-81.6
-85.2
-89.7
99.6
-85.5
-80.0
-83.8
-82.7
-83.0
-81.7
-------
Table A.4.3-3. SEL of blast events through a C-weighting network or an
A-weighting network. All in dB re 20 p pascals.
Blast
No.
Outdoor
C-Weighted SEL
Air Wave
Indoor
C-Weighted SEL
Ground Wave Air Wave
Indoor
A-Weighted SEL
Air Wave
1
-
75.2
66.0
-
2
-
84.2
85.2
-
3
-
83.3
75.8
-
4
-
81.6
83.2
-
5
7.7.6
76.5
71.7
54.7
6
-
79.7
80.8
52.5
7
83.6
90.0
83.0
55.9
8
-
71.2
82.3
49.5
9
83.9
71.7
81.5
54.0
10
92.1
72.5
86.4
51.7
11
85.2
69.5
78.1
48.7
12
-
82.5
71.2
-
13
-
68.2
71.2
-
14
101.2
-
-
61.7
15
92.5
-
-
49.9
16
88.1
-
-
44.7
17
83.6
-
-
47.3
18
87.9
-
-
54.2
A-53
-------
I • J
Las
^o.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
Slow meter response of blast events through a 4 Hz to 200 Hz
filter. Sound pressure data in dB re 20 p pascals and velocity
data in dB re 1 meter per second.
Outdoor Velocity Outdoor Sound
in meters/sec Pressure in
L V dB re 20 y pa
-63.2
-66.0
98.0
-64.5
-73.0
90.0
-69.2
-70.2
91.0
-74.3
-71.0
82.5
-71.6
-70.0
89.0
-60.0
-67.2
94.3
-80.5
-86.0
91.0
-80.2
-83.5
94.0
-75.0
-79.8
98.2
-79.3
-83.8
93.0
-71.0
-76.0
-
-79.0
-81.0
83.2
CN
ID
CO
1
-87.0
103.0
-78.9
-80.0
98.0
-77.0
-82.0
99.0
-86.8
-88.8
88.0
-83.2
-92.0
95.0
A-5 4
-------
Table A.4.3-5. Slow meter response of blast events through a C-weighting
network. Sound pressure data in dB re 20 y pascals, and
velocity data in dB re 1 meter per second.
Outdoor Velocity Outdoor Sound
Blast in meters/sec Pressure in
No. L V dB re 20 y pa
1
-
-
-
2
-66.9
-69.6
89.8
3
-74.8
-78.7
82.5
4
-72.9
-73.8
81.9
5
-78.4
-73.7
73.7
6
-76.8
-73.3
80.7
7
-72.4
-74.7
82.6
8
-76.5
-88.3
85.2
9
-85.1
-86.6
83.0
10
-78.4
-81.5
89.8
11
-82.2
-85.3
84.6
12
-73.8
-77.5
-
13
-85.4
-84.9
76.0
14
-93.8
-99.0
93.0
15
-81.8
-81.9
91.0
16
-80.7
-84.4
87.0
17
-91.4
-90.8
82.0
18
-89.1
-95.4
87.0
A-55
-------
Table A.4.3-6, Outdoor sound pressure measurements of blast events made by
Illinois Environmental Protection Agency in 1976 on quarry
or coal mine property. All in dB re 20 y pascals
Blast
No.
Distance
(meters)
Max Charge
Per Delay
(K grams)
Peak Sound
Pressure Level
SEL
4-200 Hz
Slow Response
4-200 Hz
Slow Response
C-weighted
1
130
30.8
117
103.4
100
98
2
229
30.8
122
105.5
100
97
8
396
30.8
132
110.7
110
109
9
254
61.2
127
113.5
112
105
10
315
30.8
131
108.4
105
102.5
11
372
30.8
133
107.4
104
100
12
396
30.4
115
100.2
96
95.5
19
512
95.2
123
108.6
106.5
99
20
512
95.2
121
100.5
103.2
95.3
21
512
136.1
131
106.5
106.8
103.6
22
376
381.0
136
120.5
118.2
110.7
23
396
340.2
127
117.1
114
106.0
24
152
385.6
133
116.0
113.5
111.5
25
412
476.3
140
125.0
122.1
114.8
26
412
476.3
145
130.3
128.5
120.7
A-56
-------
squared and integrated with a true integrator having a 1-second
time constant to obtain SEL or VEL. This data is presented in
Table A.4.3-2.
The sound pressure level measurements recorded both inside and
outside were sent through a standard C-weighted network and
analysed to obtain CSEL. The A-weighted sound level recorded
inside the dwelling was analyzed in the same manner. This reduced
data is presented in Table A.4.3-3.
All outdoor sound data and many outdoor velocity measurements were
passed through a conventional sound-level meter containing an
external band-pass filter from 4 to 200 Hz. The maximum meter
reading on slow response was recorded and the results are presented
in Table A.4.3-4.
A similar experiment was conducted utilizing the conventional
C-weighting network on the sound-level meter. Again, the maximum
reading obtained with a slow meter response is shown in Table
A.4.3-5.
These various descriptors were also used to analyze the outdoor
air blast sound recordings made by Illinois EPA. The results of
the analysis are shown in Table A.4.3-6.
A-57
-------
In addition to the blast noise and vibration measurements taken
inside and outside the selected dwellings, data was obtained to
describe the physical characteristics of the dwelling, weather
conditions, the distance between the blast and the instrumented
dwelling, and the blast configuration. These data are presented
in Appendix B together with the sound and vibration results for
each blast. The information is also summarized in Table A.4.3-7.
A-58
-------
Table
A.4.3-7. Physical data on quarry blasts measured by Kamperman Associates Inc. during August, September
and October, 1976
Distance
from
Maximum
charge/
Total
Total
Orientation
Wind
speed
Orientation
Construction
31ast Blast
No. (m)
delay
(kg)
charge
(kg)
time
(msec)
from
blast face
(km/
sec)
of wind
from blast
# of
floors
Frame
Outer wall
Basement,
concrete
1
1100
30.8
604
392
180°
9
0°
1
wood
brick veneer
half poured,
half grade slab
2
457
30.8
695
392
45°
10
0°
1
wood
brick veneer
poured
3
1280
317.5
3975
-
45°
10
45°
2
wood
brick veneer
poured
4
549
59.0
824
168
135°
-
-
2
wood
brick veneer
poured
5
579
30.4
531
266
180°
16
90°
1
wood
brick veneer
poured
6
655
59.0
1190
266
180°
16
90°
1
wood
brick veneer
poured
7
1128
317.5
3954
-
180°
20
45°
1
wood
wood
block
8
1067
30.8
762
378
45°
24
0°
1
wood
wood
block
9
1006
61.2
1165
238
45°
24
0°
1
wood
wood
block
10
646
30.8
911
462
90°
16
0°
1
wood
brick veneer
poured
11
701
30.8
530
266
45°
24
0°
1
wood
brick veneer
poured
12
701
30.4
3039
1372
-
16
45°
Tri-
level
wood
brick veneer
poured
13
610
30.4
882
408
90°
24
0°
2
brick
brick
block
14
1600
226.8
2555
210
0
20
0
2
steel
concrete
block
slab
15
762
31.8
740
378
45°
8
45°
Tri-
level
wood
wood
poured
16
716
31.8
529
210
45°
8
45°
Tri-
level
wood
wood
poured
17
1067
30.8
579
350
45°
16
0°
1
wood
brick veneer
block
18
1128
30.8
419
266
135°
24
0°
1
wood
brick veneer
block
Downwind is 0°, upwind is 180°.
-------
APPENDIX B
DETAILED TIME HISTORY OF 18 RECORDED STONE QUARRY BLAST EVENTS
BY KAMPERMAN ASSOCIATES INC.
The signals and time (1-second markings) are displayed on a
linear scale. The signal levels are not calibrated in absolute
values. However, for any particular blast, the three outdoor
velocity pickups have the same gain, the outdoor and indoor
microphones (on traces 4 and 5) have the same gain, and the
three indoor velocity pickups have the same gain (although it
may be different from the outdoor pickups). The oscillograph
records were displayed for easy viewing of the events vs time.
The absolute peak values for each trace are summarized in
Table A.4.3-1.
B-l
-------
Quarry Blast No. 1
Distance from home to blast:
Direction of home from blast:
Home construction:
Wind direction out of the:
Wind speed:
Temperature:
Temperature profile:
Cloud cover:
Depth of blast below grade level:
Total charge of blast:
Maximum charge per delay:
Number of holes:
Depth of holes:
Number of delays.:
Time between delays:
Total time of blast:
Blast face orientation:
1100 meters
West
1 floor with half basement, wood
frame, brick veneer
East-Northeast
9 K meters/hour
26 °C
Neutral
Hazy
4 5 meters
60 4 K grams
31 K grams/delay
14
6 meters
28
12 mseconds
392 mseconds
East
B-2
-------
Indoor
Sound
Pressure
Vertical
Floor
Acceleration
Indoor
Sound
Pressure
Vertical
Floor
Velocity
r
r
i-
03
I
U>
Fig. B-l.
Oscillograph Record of Blast No. 1
-------
Quarry Blast No. 2
Distance from home to blast:
Direction of home from blast:
Home construction:
Wind direction out of the:
Wind speed:
Temperature:
Temperature profile:
Cloud cover:
Depth of blast below grade level:
Total charge of blast:
Maximum charge per delay:
Number of holes:
Depth of holes:
Number of delays:
Time between delays:
Total time of blast:
Blast face orientation:
457 meters
Northwest
1 floor with basement, wood frame,
brick veneer
East-Northeast
10 K meters/hour
28°C
Lapse
Clear
45 meters
695 K grams
31 K grams/delay
14
6 meters
28
12 mseconds
392 mseconds
North
B-4
-------
Outdoor
Lateral
Velocity
Outdoor
Transverse
Veloci ty
Outdoor
Verti cal
Veloci ty
Outdoor
Sound
Pressure
Indoor
Sound
Pressure
Vertical
Floor
Acceleration
Indoor
Sound
Pressure
Vertical
Floor
Velocity
00
cn
-o
SO
O
o
cz
o
CO
S ^ 5 s
1 sec -»¦
Oscillograph Record of Blast No. 2
-------
Quarry Blast No. 3
Distance from home to blast:
Direction of home from blast:
Home construction:
Wind direction out of the:
Wind speed:
Temperature:
Temperature profile:
Cloud cover:
Depth of blast below grade level:
Total charge of blast:
Maximum charge per delay:
Number of holes:
Depth of holes:
Number of delays:
Time between delays:
Total time of blast:
Blast face orientation:
1280 meters
West
2 floors with basement, wood
brick veneer
Northeast
10 K meters/hour
33 °C
Lapse
Clear
4 3 meters
3975 K grams
318 K grams/delay
6
4 3 meters
24
40, 100, 120 and 150 mseconds
Southeast
B-6
-------
Outdoor
Lateral
Velocity
Outdoor
Transverse
Veloci ty
Outdoor
Verti cal
Velocity
Outdoor
Sound
Pressure
Indoor
Sound
Pressure
Vertical
Floor
Acceleration
Indoor
Sound
Pressure
Vertical
Floor
Velocity
-o
30
o
o
c=
o
03
TO
I
Fig, B-3. Oscillograph Record of Blast No. 3
-------
Quarry Blast No. 4
Distance from home to blast:
Direction of home from blast:
Home construction:
Wind direction out of the:
Wind speed:
Temperature:
Temperature profile:
Cloud cover:
Depth of blast below grade level:
Total charge of blast:
Maximum charge per delay:
Number of holes:
Depth of holes:
Number of delays:
Time between delays:
Total time of blast:
Blast face orientation:
549 meters
West
2 floors with basement, wood frame,
brick veneer
None
0 K meters/hour
27 °C
Neutral
Hazy
70 meters
824 K grams
59 K grams/delay
13
10 meters
13
14 mseconds
168 mseconds
Southeast
B-8
-------
Outdoor
Lateral
Velocity
Outdoor
Transverse
Veloci ty
Outdoor
Vertical
Veloci ty
Outdoor
Sound
Pressure
Indoor
Sound
Pressure
Vertical
Floor
Acceleration
Indoor
Sound
Pressure
Vertical
F1 oor
Veloci ty
-\yv7v.
MMMMIWMVMttMp
CO
I
VO
Fig. B-4.
w 1
t- r
I
h
D CD C
V _J c
.
3
D
1 sec
V 5
I jrtbfc
Oscillograph Record of Blast No. 4
-T3
za
o
o
d
OD
-------
Quarry Blast No. 5
Distance from home to blast:
Direction of home from blast:
Home construction:
Wind direction out of the:
Wind speed:
Temperature:
Temperature profile:
Cloud cover:
Depth of blast below grade level:
Total charge of blast:
Maximum charge per delay:
Number of holes:
Depth of holes:
Number of delays:
Time between delays:
Total time of blast:
Blast face orientation:
579 meters
West
1 floor with basement, wood frame,
brick veneer
South
16 K meters/hour
24°C
Neutral
80% and hazy
70 meters
531 K grams
30 K grams/delay
10
10 meters
20
14 mseconds
266 mseconds
East
B-10
-------
Outdoor
Lateral
Veloci ty
Outdoor
Transverse
Veloci ty
Outdoor
Vertical
Veloci ty
Outdoor
Sound
Pressure
Indoor
Sound
Pressure
Verti cal
Floor
Veloci ty
Lateral
Wall
Veloci ty
Transverse
Wall
Velocity
-------
Quarry Blast No. 6
Distance from home to blast:
Direction of home from blast:
Home construction:
Wind direction out of the:
Wind speed:
Temperature:
Temperature profile:
Cloud cover:
Depth of blast below grade level:
Total charge of blast:
Maximum charge per delay:
Number of holes:
Depth of holes:
Number of delays:
Time between delays:
Total time of blast:
Blast face orientation:
655 meters
West
1 floor with basement, wood frame,
brick veneer
South
16 K meters/hour
27 °C
Lapse
Clear
70 meters
1190 K grams
59 K grams/delay
10
10 meters
20
14 mseconds
266 mseconds
East
B-12
-------
Outdoor
Lateral
Velocity
Outdoor
Transverse
Velocity
Outdoor
Vertical
Veloci ty
Outdoor
Sound
Pressure
Indoor
Sound
Pressure
Lateral
Floor
Velocity
Transverse
Floor
Velocity
Vertical
Floor
Velocity
00
CO
Fig. B-6.
«-1 sec -*
Oscillograph Record of Blast No. 6
-------
Quarry Blast No. 7
Distance from home to blast:
Direction of home from blast:
Home construction:
Wind direction out of the:
Wind speed:
Temperature:
Temperature profile:
Cloud cover:
Depth of blast below grade level:
Total charge of blast:
Maximum charge per delay:
Number of holes:
Depth of holes:
Number of delays:
Time between delays:
Total time of blast:
Blast face orientation:
1128 meters
West
1 floor, wood frame bungalow,
full basement
South
20 K meters/hour
31°C
Lapse
Hazy - no clouds
43 meters
3954 K grams
317.5 K grams/delay
6
43 meters
24
40, 100, 120 or 150 mseconds
North-Northeast
B-14
-------
Outdoor
Lateral
Velocity
Outdoor
Transverse
Velocity
Outdoor
Vertical
Velocity
Outdoor
Sound
Pressure
Indoor
Sound
Pressure
Lateral
Floor
Veloci ty
Transverse L .
Floor
Velocity ' 1
Vertical
Floor
Velocity
m
-o
TO
O
o
c
o
CO
CO
I
Fig. B-7.
+-1 sec ->-
Oscillograph Record of Blast No. 7
-------
Quarry Blast No. 8
Distance from home to blast:
Direction of home from blast:
Home construction:
Wind direction out of the:
Wind speed:
Temperature:
Temperature profile:
Cloud cover:
Depth of blast below grade level:
Total charge of blast:
Maximum charge per delay:
Number of holes:
Depth of holes:
Number of delays:
Time between delays:
Total time of blast:
Blast face orientation:
1067 meters
Northeast
1 floor with basement, wood frame
South-Southwest
24 K meters/hour
26 °C
Lapse
50%
45 meters
762 K grams
31 K grams/delay
14
10 meters
28
14 mseconds
378 mseconds
East
B-16
-------
Outdoor
Lateral
Veloci ty
Outdoor
Transverse
Veloci ty
Outdoor
Vertical
Velocity
Outdoor
Sound
Pressure
Indoor
Sound
Pressure
Lateral
Floor
Veloci ty
Transverse
Floor
Veloci ty
Vertical
Floor
Veloci ty
U3
I
-o
TO
O
o
cr
o
OD
<- 1 sec ¦*
Oscillograph Record of Blast N
-------
Quarry Blast No. 9
Distance from home to blast:
Direction of home from blast:
Home construction:
Wind direction out of the:
Wind speed:
Temperature:
Temperature profile:
Cloud cover:
Depth of blast below grade level:
Total charge of blast:
Maximum charge per delay:
Number of holes:
Depth of holes:
Number of delays:
Time between delays:
Total time of blast:
Blast face orientation:
1006 meters
Northeast
1 floor with basement, wood frame
South-Southwest
24 K meters/hour
27°C
Lapse
100%
45 meters
116 5 K grams
61 K grams/delay
17
10 meters
17
14 mseconds
238 mseconds
East
B-18
-------
Outdoor
Lateral
Velocity
Outdoor
Transverse
Veloci ty
Outdoor
Vertical
Veloci ty
Outdoor
Sound
Pressure
Indoor
Sound
Pressure
Lateral
Floor
Veloci ty
Transverse
Floor
Veloci ty
Vertical
Floor
Veloci ty
T5
ZO
o
o
c:
CD
CD
00
1
.1. Lf1
CD
CD
Fig. B-9.
¦*- 1 sec |
Oscillograph Record of Blast No. 9
-------
Quarry Blast No. 10
Distance from home to blast:
Direction of home from blast:
Home construction:
Wind direction out of the:
Wind speed:
Temperature:
Temperature profile:
Cloud cover:
Depth of blast below grade level:
Total charge of blast:
Maximum charge per delay:
Number of holes:
Depth of holes:
Number of delays:
Time between delays:
Total time of blast:
Blast face orientation:
646 meters
North
1 floor with basement, wood frame
brick veneer
South
16 K meters/hour
22°C
Neutral
Clear
70 meters
911 K grams
31 K grams/delay
17
10 meters
34
14 mseconds
462 mseconds
East
B-20
-------
Outdoor
Lateral
Velocity
Outdoor
Transverse
Velocity
Outdoor
Vertical
Velocity
Outdoor
Sound
Pressure
Indoor
Sound
Pressure
Lateral
Floor
Veloci ty
Transverse
Floor
Velocity
Vertical
Floor
Velocity
# \ i M|i I'j r, Ji !| )i m f, ft ^ n , u I
L: J i:' | ,j 11! jjj ;i :/y yy
-c h tn cr
CD
I
ro
Fig. B-10. Oscillograph Record of Blast No. 10
O
CD
1 sec
"O
70
O
o
c:
o
03
-------
Quarry Blast No. n
Distance from home to blast:
Direction of home from blast:
Home construction:
Wind direction out of the:
Wind speed:
Temperature:
Temperature profile:
Cloud cover:
Depth of blast below grade level:
Total charge of blast:
Maximum charge per delay:
Number of holes:
Depth of holes:
Number of delays:
Time between delays:
Total time of blast:
Blast face orientation:
701 meters
North
1 floor with basement, wood frame,
brick veneer
South
24 K meters/hour
24°C
Lapse
Clear
70 meters
530 K grams
31 K grams/delay
10
10 meters
19
14 mseconds
266 mseconds
Northeast
B-22
-------
Outdoor
Lateral
Velocity
Outdoor
Transverse
Velocity
Outdoor
Vertical
Velocity
Outdoor
Sound
Pressure
Indoor
Sound
Pressure
Lateral
Floor
Velocity
Transverse
Floor
. Velocity
Vertical
Floor
Velocity
O O CD O
— nj uj -c
CD cd a
Ln cr -j
o
CD
1 sec
? Fig. B-l1. Oscillograph Record of Blast No. U
no
CO
-------
Quarry Blast No. 12
Distance from home to blast:
Direction of home from blast:
Home construction:
Wind direction out of the:
Wind speed:
Temperature:
Temperature profile:
Cloud cover:
Depth of blast below grade level:
Total charge of blast:
Maximum charge per delay:
Number of holes:
Depth of holes:
Number of delays:
Time between delays:
Total time of blast:
Blast face orientation:
701 meters
North
Tri-level, wood frame, brick veneer
Southwest
16 K meters/hour
26°C
Lapse
20%
81 meters
3039 K grams
30 K grams/delay
99
30 meters
99
14 mseconds
1372 mseconds
Up
B-24
-------
Outdoor
Lateral
Velocity
Outdoor
Transverse
Veloci ty
Outdoor
Vertical
Velocity
Indoor
Sound
Pressure
Lateral
Floor
Velocity
Vertical
Floor
Velocity
P 1 ^
M; WU,'. , -
r't .I' l«'V
¦|i
i" r
i-
Va I*^¥*=ftsiva ¦^UJxAqea
V- t
1 ¦ i
r p
CDOC3CDOOCDC3
ruUJ-CLPCr-JCD
«- 1 sec -+
^ Fig. B-12. Oscillograph Record of Blast No. 12
cn
-------
Quarry Blast No. 13
Distance from home to blast:
Direction of home from blast:
Home construction:
Wind direction out of the:
Wind speed:
Temperature:
Temperature profile:
Cloud cover:
Depth of blast below grade level:
Total charge of blast:
Maximum charge per delay:
Number of holes:
Depth of holes:
Number of delays:
Time between delays:
Total time of blast:
Blast face orientation:
610 meters
Northeast
2-story brick, wood floors, basement:
Southwest
24 K meters/hour
2 3 °C
Neutral
Clear
31 meters
882 K grams
31 K grams/delay
11
15.5 meters
33
25 mseconds
4 08 mseconds
Northwest
B-26
-------
Outdoor
Lateral
Velocity
Outdoor
Transverse
Velocity
Outdoor
Vertical
V e 1 oc i ty
Outdoor
Sound
Pressure
Indoor
Sound
Pressure
Lateral
Floor
Velocity
Transverse
Floor
Veloci ty
Vertical
Floor
Veloci ty
wwwaaA/W\ m
"U
3D
o
o
o
TO
1 sec
co Fig. B-13. Oscillograph Record of Blast No. 13
ro
-------
Quarry Bl^st No. 14
Distance from home to blast:
Direction of home from blast:
Home construction:
Wind direction out of the:
Wind speed:
Temperature:
Temperature profile:
Cloud cover:
Depth of blast below grade level:
Total charge of blast:
Maximum charge per delay:
Number of holes:
Depth of holes:
Number of delays:
Time between delays:
Total time of blast:
Blast face orientation:
1600 meters
North
2 floors, concrete block walls, pre-
stressed concrete slabs, 3-inch
concrete floor covering
South
20 K meters/hour
18 °C
Lapse
Clear
30 meters
2555 K grams
227 K grams/delay
4
30 meters
16
14 mseconds
210 mseconds
North-Northeast
B-28
-------
Outdoor
Lateral
Veloci ty
Transverse
r h r
Veloci ty
Outdoor
Vertical
Veloci ty
Outdoor
Sound
Pressure
Verti cal
Floor
Acceleration
Lateral
Floor
Velocity
Transverse
Floor
Veloci ty
Vertical
Floor
Velocity
"O
ZXD
O
O
cz
o
UJ
CD
I
ro
Fig. B-14. Oscillograph Record of Blast No. 14
-------
Quarry Blast No. 15
Distance from home to blast:
Direction of home from blast:
Home construction:
Wind direction out of the:
Wind speed:
Temperature:
Temperature profile:
Cloud cover:
Depth of blast below grade level:
Total charge of blast:
Maximum charge per delay:
Number of holes:
Depth of holes:
Number of delays:
Time between delays:
Total time of blast:
Blast face orientation:
762 meters
North
Tri-level, wood frame, brick veneer
Southeast
8 K meters/hour
11°C
Inversion
Clear
4 5 meters
740 K grams
32 K grams/delay
14
10 meters
28
14 mseconds
378 mseconds
Northeast
B-30
-------
Outdoor
Lateral
Velocity
Outdoor
Transverse
Velocity
Outdoor
Vertical
Veloci ty
Outdoor
Sound
Pressure
Vertical
Floor
Acceleration
Lateral
Floor
Velocity
Transverse
Floor
Velocity
Vertical
Floor
Velocity
U3
I
CO
1 sec
Fig. B-15. Oscillograph Record of Blast No. 15
-------
Quarry Blast No. 16
Distance from home to blast:
Direction of home from blast:
Home construction:
Wind direction out of the:
Wind speed:
Temperature:
Temperature profile:
Cloud cover:
Depth of blast below grade level:
Total charge of blast:
Maximum charge per delay:
Number of holes:
Depth of holes:
Number of delays:
Time between delays:
Total time of blast:
Blast face orientation:
716 meters
North
Tri-level, wood frame, brick veneer
Southeast
8 K meters/hour
16 °C
Lapse
Clear
4 5 meters
529 K grams
32 K grams/delay
8
10 meters
16
14 mseconds
210 mseconds
Northeast
B-32
-------
Outdoor
Lateral
Veloci ty
Outdoor
Transverse
Velocity
Outdoor
Vertical
V e1oc i ty
Outdoor
Sound
Pressure
Verti cal
Floor
Acceleration
Lateral
Floor
Velocity
Transverse
Floor
Veloci ty
Vertical
Floor
Veloci ty
I ^
V:>;/> /^/yVv
1 it ' .
A/V\/WW^\
t- '
IT J
' Li
r i
LP PD
in p-
CD
CD
-o
ZO
o
o
cz
o
CO
CD
I
CO
CO
Fig. B-16. Oscillograph Record of Blast No. 16
1 sec
-------
Quarry Blast No. 17
Distance from home to blast:
Direction of home from blast:
Home construction:
Wind direction out of the:
Wind speed:
Temperature:
Temperature profile:
Cloud cover:
Depth of blast below grade level:
Total charge of blast: .
Maximum charge per delay:
Number of holes:
Depth of holes:
Number of delays:
Time between delays:
Total time of blast:
Blast face orientation:
1067 meters
North
1 floor, wood frame, with basement
South
16 K meters/hour
16 °C
Neutral
Clear
45 meters
57 9 K grams
31 K grams/delay
13
10 meters
26
14 mseconds
350 mseconds
Southeast
B-34
-------
Outdoor
Lateral
Veloci ty
Outdoor
Transverse
Veloci ty
Outdoor
Vertical
Velocity
Outdoor
Sound
Pressure
Vertical
F1 oor
Acceleration
Lateral
Floor
Velocity
Transverse
Floor
Velocity
Vertical
Floor
Veloci ty
CO
I
GO
c_n
Vi^Z-vA*\V/v»v
\.V//WvvvvV^v»«wJW^ ^rVvvV^/wVywVV'V'W'^v^ i^*=sy«V^a^Mfe^wsa
r
Fig. B-17.
t
n.<
ri^
C.T
Oscillograph Record of Blast No. 17
/v^wvvAw
cm
CD
*- 1 sec
-------
Quarry Blast No. 18
Distance from home to blast:
Direction of home from blast:
Home construction:
Wind direction out of the:
Wind speed:
Temperature:
Temperature profile:
Cloud cover:
Depth of blast below grade level:
Total charge of blast:
Maximum charge per delay:
Number of holes:
Depth of holes:
Number of delays:
Time between delays:
Total time of blast:
Blast face orientation:
1128 meters
North
1 floor, wood frame, with basement
South
24 K meters/hour
21 °C
Lapse
Clear
4 5 meters
419 K grams
31 K grams/delay
10
10 meters
20
14 mseconds
266 mseconds
East
B-36
-------
Outdoor
Lateral
Velocity
Outdoor
Transverse
Velocity
Outdoor
Vertical
Velocity
Outdoor
Sound
Pressure
Lateral
Floor
Veloci ty
Transverse
Floor
Velocity
Vertical
Floor
Velocity
MA ii ¦
r j'i1 1 ; ; i
p 'V '(,W/V
------- |