Peak Particle Velocity variation in soil and rock
Peak Particle Velocity variation in soil and rock
(OP)
I am looking for references or information on peak particle velocity variation in rock and soil. We are working on a new commercial building which on two occasions showed damage immediately after blasting to the footings and masonry block walls. The building foundations are on rock, however, the seismograph was spiked in soils above the rock. The seismograph data was well within acceptable ranges although damage was observed that could only be attributable to the blasting (damage occurred immediately at time of blasts). Blast frequency was in 25 to 35 hz range, with PPV of .17 to .63 in/sec. Air Blast ranged from 115 to 137 decibels.





RE: Peak Particle Velocity variation in soil and rock
RE: Peak Particle Velocity variation in soil and rock
http://www.eng-tips.com/viewthread.cfm?spid=256&newpid=256&sqid=61566
RE: Peak Particle Velocity variation in soil and rock
Also, depending on how close you were to the blasting when setting up the seismograph, you could not be recording the correct data. The seismograph could have had its limits exceeded due to extremely high accelerations or frequencies and had aliasing or decoupling occur.
It is extremely rare to cause blast damage unless there was very high displacements or you had actual rock movement under the building.
We blast consistently within 1/2 foot of structures without problems, but, proper seismograph placement is the key to insure that we are getting the correct information during the test blast program to aid in actual blast design for the production blasting.
I have written a paper on close-in blasting. Go to www.terradinamica.com, the "Tech Talk" page. You can download it there in .pdf.
Frank Lucca M.I.Exp.E.
www.terradinamica.com
RE: Peak Particle Velocity variation in soil and rock
Bob Cummings
Geological Engineer
RE: Peak Particle Velocity variation in soil and rock
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RE: Peak Particle Velocity variation in soil and rock
RE: Peak Particle Velocity variation in soil and rock
Where is the site? It sounds like you are on the U.S. west coast.
Give us a clearer picture of the footing and subgrade dimensions, particularly with respect to the crack. That might help us understand what's going on, and offer better observations and suggestions.
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RE: Peak Particle Velocity variation in soil and rock
Lou Oriard wrote a prety good book on blast damage to structures, focusing on how to interpret the cause from the crack configurations. It is titled Effects of Vibrations and Environmental Forces, published by the International Society of Explosives Engineers (http://www.isee.org). also see Oriard's other book, Explosives Engineering, Construction Vibrations and Geotechnology, published also by ISEE.
Oriard is a realist and one of the clearest thinkers in this field.