Backfill has many good points. If the load bearing is a sensitive or valuable structure, backfill the void, or excavate it out. Drill hole cameras can be placed to survey the void and its condition. Good luck, indeed.
This is NOT a simple question. It is a highly three-dimensional problem. You will be best modeling the situation using some finite element or discrete element code -- not for amateurs. Simple beam theory does not account for the geometrics and fracturing.
Best thing is a tall fluorescent red flag to get above dust and to be at truck driver's eye level. Also, flashing light helps. Also in the US, NIOSH (former USBM) has done a lot of work on this topic. They are at http://www.cdc.gov/niosh/mining/default.htm.
This is not really my field, but I have done a great deal of work in rock reinforcement and ground anchors. Galvanizing would be breached during torqueing, when the threads would be in tight contact. There are any number of protective coatings that can be painted on after the installation.
This is an everyday problem in the chemical lime and portland cement quarry/mine industries. There are numerous labs that offer this service. Sampling must be done properly to avoid contamination and misrepresentation. Are you using diamond holes, rotary holes, RC holes, bulk?
Chunil -- What is it you are trying to do? What are you building/excavating? What rock mass propertiess do you need? I think you are discovering that you are in that never-never shadow land between rock and soil, where neither rules do well.
Situation was three sides free, very flat dip on bedding, VERY crowded shot with little relief. You should see the videos! Put rock into orbit. Thanks, all.
I am looking for any case histories of a quarry-type blast pushing un-shot rock around it by gliding on a bedding plane. I'm not talking small stuff. The incident I'm working on is a block over 100 ft on a side over ten feet thick moving several feet.
Before going to al of this expensive and potentially damaging remedial foundation work, I would get a quote from a housemover to move the house to a nearby site where you have drilled to see if peat and silt are present.
If your lot is too small, have the house moved off the lot, excavate out...
Ron Graber of Cleveland Cliffs in Upper Michigan has done a lot of work with GPS on trucks for scheduling in an iron ore mine. He can be reached at rggraber@cci-cmsc-mi.com.
If rainfall/precipitation is an issue. The best data is from NOAA at http://www.ncdc.noaa.gov/oa/ncdc.html. Costs just $10.00 per set. Otherwise it's hearsay. Also local newspapers almost always have archives on the Internet. Make sure you get ALL of the construction, design, and...
Try registering with the Defense Reasearch Institute (No, it is not a Pentagon think tank, but a defense lawyer's group for insurance and property/casaulty losses). They're at www.dri.org . It's free to register.
There are several brokers out there and I have never used them. Make sure you have a web site connected into google and use key words descriptive of what you do. That's how a lot of our attorney work comes in, other than referral.
