RI 8506 Measurement of Blast-Induced Ground Vibrations and Seismograph Calibration

Jul 10, 2000

M. Stagg & A. Engler

RI 8506 Measurement of Blast-Induced Ground Vibrations and Seismograph Calibration 
 
    
 MEASUREMENT OF BLAST-INDUCED GROUND VIBRATIONS
AND SEISMOGRAPH CALIBRATION
 
 Mark S. Stagg, Civil Engineer
Alvin J. Engler, Electronics Engineer 
 
 Twin Cities Research Center, Bureau of Mines, Twin Cities, Minn. 
 
 ABSTRACT
 
 Blast-induced ground vibrations from surface coal mine, quarry, and construction blasting 
were measured and analyzed for frequency content and duration characteristics. Eighteen 
commercially available ground vibration measurement systems were evaluated in the field 
and laboratory for linearity, accuracy, and crosstalk, Buried, surface, and sandbagged 
transducer placement methods were compared, along with peak and vector-sum 
measurements
 
 The recommended minimum frequency ranges for ground vibration instrumentation are 2 
to 150 Hz for coal mine and quarry blasting, and 5 to 200 Hz for construction and 
excavation blasting. When higher or lower frequency vibrations are possible, as in 
construction blasting or for a quarry shot close to a residence, care should be taken to 
insure proper choices of instrumentation and vibration criteria.
 
 Several instruments operating in these ranges are available, and all but one of the 
seismographs tested fell within ±3-dB accuracy limits (+41 pct, -29 pct).
 
 Waveform recordings of all three ground vibration components are recommended as the 
peak amplitude and frequency may vary among the three. Peak or vector-sum readings are 
adequate if only amplitude levels are desired. The soil density matched box should be 
anchored or buried, particularly for high frequency, high amplitude construction blasting.
 
 INTRODUCTION
 
 Effects of ground vibrations generated from surface blasting have been of increasing 
public concern. The growing number of surface coal mines and quarries operating in 
populated areas has caused considerable consternation for mine operators and for people 
who live nearby The Bureau of Mines has responded by conducting research on 
measurement and analysis of ground vibrations, and their effects on structures and people.
 
 Displacement seismographs and falling_pin gages were commonly the first instruments 
used to measure the effects of ground vibrations (21).3 Displacement seismographs and 
calibration tables were designed by the Bureau as part of an extensive research program 
conducted from 1930 to 1940 to study the effects of ground vibrations from quarry 
blasting (25). This study proposed that acceleration, calculated from displacement 
measurements, was the criterion most closely associated with damage. Later studies 
 
 Copyright © 2000 International Society of Explosives Engineers
RI 8506 Measurement of Blast-Induced Ground Vibrations and Seismograph Calibration - P 1 1 of 33 
  
 
   
 proposed a criterion based on particle velocity (2, 7, 13) calculated from displacement and 
acceleration measurements. Transducers were then developed to measure acceleration, 
displacement, or velocity directly. Because the velocity criterion was based on converted 
acceleration or displacement readings, two studies (8, 19) took direct measurements of 
acceleration, displacement, and particle velocity. Peak particle velocity remained the 
recommended damage criterion. Earlier studies measured the vibration at various 
locations: ceiling panels, foundation walls, and at the surface of the soil near the structure. 
Additional data were collected, using the peak particle velocity determined from the 
vector addition of all three ground vibration components (26). The Bureau reexamined the 
problem and reported results on seismograph calibration (9, 17), instrumentation design 
requirements (4-5), soil coupling of gages (11), and damage criteria based on velocity (6). 
In 1971, the results of these studies were published (18), and the industry has incorporated 
the information into the design and production of velocity seismographs. However, 
questions still remained on the effects of surface placement of transducers (1, 10, 27), the 
frequency range that should be measured, velocity seismograph calibration, and velocity 
measurement methodology. Recent publications give an overview of instrumentation and 
damage criteria (24), list frequency and scaled-distance ranges for coal, quarry, and 
construction vibrations (14), and demonstrate new measurement analysis techniques of 
velocity exposure level (12) and response spectra (3, 16). The results of analysis using 
these techniques have recently been published (23) by the Bureau.
 
 Investigation results differed depending upon the instrumentation and measurement 
method used. Frequency response characteristics, system resonances, transducer 
mounting, and other factors can alter the measured amplitude from one seismograph to 
another. The present study provides the results of calibration tests performed on 
commonly utilized seismographs from various manufacturers. Their advantages and 
disadvantages are discussed, and minimum operating parameters are recommended 
 
 ACKNOWLEDGMENTS
 
 The authors thank Joseph L. Condon, research supervisor, Denver (Colo.) Research 
Center, and David E. Siskind of Twin Cities (Minn.) Research Center, Bureau of Mines, 
for their assistance in planning and data analysis.
 
 The authors are especially indebted to James A. Gould of Philip R. Burger & Associates, 
Thomas W. Novotny of Vibra-Tech Engineers, Inc., Ray Callicoatte of Dallas Instruments, 
Inc., and Spence Lucole of VME-Nitro Consult, Inc., who assisted or provided their 
companies' vibration instrumentation for calibration.
 
 INSTRUMENTATION
 
 Ground vibration waves from a blast emanate in every direction. Of principle importance 
for instrumentation monitoring these vibration waves are their frequency (f), amplitude 
range, and duration As seen in figure 1, the wave has a peak particle velocity of 0.45 
in/sec and a duration of 1 sec, and is composed of complex frequencies, one being 28 Hz ( 
1/period = f ) . The frequency spectrum of the shot is shown to the right in the figure The 
 
 Copyright © 2000 International Society of Explosives Engineers
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 spectrum is a histogram of the frequencies present in the vibration, with the relative 
amplitudes given in decibels A seismograph is an instrument that records ground motions 
and is usually a package of three mutually orthogonal ground vibration transducers, signal 
conditioners, and a recording mechanism, such as a light-beam oscillograph or magnetic 

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