Ground Vibration - Rock Blasting

[toro22]

I am looking at a house that is claiming ground vibration damage from nearby rock blasting. The vibration levels recorded at a nearby seismograph showed that vibration levels were below accepted threshold limits for damage. The homeowner is claiming that his house is built on the same bedrock that is being blasted, resulting in potentially higher vibration levels at his house than at the seismograph.

Does anybody know of a study, paper, or any document that can be referenced that discusses the effect that the soil/rock type beneath a house has on blasting vibration propagation? That is, is there a study that shows that ground vibration propagates more / less efficiently through rock than soil and if so by how much?

Thanks

 

[cvg]

unless you did a pre blast survey, good luck proving it

 

[GeoPaveTraffic]

If the house sits on rock, then the house will have felt different vibrations than a seismograph that was sitting on soil. Whether the vibrations were greater or less depends on a multitude of factors including type of rock, quality of rock, type of soil, depth of soil, and probably several more that just aren't coming to mind at the moment.

As cvg pointed out, if there wasn't a precondition survey of the house; the contractor should expect to pay up.

If additional blasting is planned, then a second seismograph could be placed in the house and the readings compared.

Mike Lambert

 

[miningman]

As an engineer who possesses a number of blasting licences, I can place seimomogragh in any given location in such a manner to record either a high or low yalue, depending on what I would like to see. I wouldn't want to defend my blasters in a case like this unless I had done a pre blast survey as previously suggested.

And if additional blasting is performed and I chose to monitor at the house, I would want the seismograph to be positioned by someone like myself who understands the practicalities of blasting like I do rather than a young inexperienced technician.

And if I was defending my blasters I would probably have them change the blast timing in a way that might be almost invisible to less experienced individual. In other words , new monitoring could not be accurately extrapolated to earlier blasts.

 

[ebenozen]

There is no reliable thoretical method to do what you're asking about toro. The preferred method of esablishing relationships between vibration or peak particle velocity and blast size is to use Oriard's scaled distance relationship which is based on blast monitoring data specific to the project site.

To prove/disprove the homeowner's point, you'd have to place seismographs on the granite near the home.

 

[dik]

About the best you can do is to examine the damage and try to determine if the damage is old or new... look for weathered edges, the inclusion of dust (possibly from rain condensation nuclei, windblown), mite webs, whatever... if damage cannot be shown as 'old' or existing... you may not have much success...

Lesson to be learned is placement of seismographs and detailed pre-damage reports...

Dik