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At what depth do sinkholes begin to pose a risk?

learning2geotech

Civil/Environmental
Apr 4, 2019
41
Let's say I have sinkholes at 50' and I want to build lightly-loaded buildings that the loads will not be anywhere near the sinkholes. Minimal grade changes. Clayey soils over limestone bedrock. No sign of sinkhole in the neighborhood but there are reported depressions in greater nearby areas according to geology maps. What kind of risk am i looking at in this scenario?
 
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I just read a STRUCTURE mag article about a building designed/built over an abandoned coal mine. Anything is possible.

That said, I don’t know enough geotech to give you a good answer, but my understanding is that certain sinkholes can open up anytime. Building or no building. Overlying soil bridges over the eroding rock until it can’t. Idk how you get around that without serious moisture control or a bigboi foundation.
 
I just read a STRUCTURE mag article about a building designed/built over an abandoned coal mine. Anything is possible.

That said, I don’t know enough geotech to give you a good answer, but my understanding is that certain sinkholes can open up anytime. Building or no building. Overlying soil bridges over the eroding rock until it can’t. Idk how you get around that without serious moisture control or a bigboi foundation.
What's the name of the article? Can you please share the link to it or upload it?
 
Do you have sinkholes below grade, or a cave? Most limestone caves I have seen firsthand have a solid layer of rock along the roof of the cavern. A sinkhole below grade (having been filled) is a huge problem waiting to happen; it will most likely open back up when the fill dirt has washes into the cave. Sinkhole = water drainage point, and water flowing at the bottom will eventually erode the fill. If you do happen to have a regular limestone cave below, it seems unlikely that a lightly loaded, small building would be an issue. The cave pictured below is in Tennessee and has shopping centers and neighborhoods over it.

capshaw cave.jpg
 

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