- Joined
- Feb 13, 2003
- Messages
- 5,475
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- Ottawa, Canuckistan
- Corvette
- 1973 coupe L82 (gone as casualty of divorce)
I did a bit of reading last night about sink holes and that is what usually happens. Unbridled curiosity. I'm not expert so don't take this to the bank!It looks like the sink hole was there and then the floor collapsed later. :confused
Water washes away limestone or other porous rock, creating a cave. This undermines whatever is above the new cave. If there is nothing but soil above, the dirt sometimes liquifies enough to gum things up so it doesn't drop precipitously. If something rigid is above, whether that is non-porous rock shelf or man-made structure, it will often remain intact until completely undermined and then it drops, hard and fast. The strange part is that this process doesn't necessarily take years as one might suppose. If the limestone was plugging an artesian water aquifer, once the limestone is gone, the aquifer can undermine the ground in a matter of days.
If the sink hole is detected before it drops, it can sometimes be prevented by pumping hydraulic mud and concrete in under pressure.
Mac