Net bearing pressure

[TDC84]

Is the net allowable bearing pressure in excess of what the previous in-situ stress was, or in excess or the adjacent pressure?

For example, say I have a basement with a wall footing. The footing is 10' deep the basement floor is 8' deep. Am I calculating the net pressure in excess of density*10' or density*2'?

If it's the latter, it seems like you could have a fully compensated foundation and still have a bearing capacity failure?

 

[oldestguy]

Wall footings are interesting. One side has an excavation unloading and the other gas no unloading. I'd guess most designers neglect any unloading to be safe.

 

[geomane]

See if this helps.