forensic rumor with infiltration chambers

[darthsoilsguy2]

i heard through the grapevine of a project where infiltration open-bottom parabolic storm chambers were installed near a new building. The chambers were above the 1:1 influence zone, but there is a theory being floated around that the soils heaved up from below into the chambers and are causing building settlement.... which makes some sense because there is no overburden pressure at those planes and there might also be some effective weight of soil issues in play during saturation. Curious if people have crossed these concerns with these buried infiltration chambers, not sure if that really counts as a question? I'm seeing on-site infiltration being required more and more for sites with space constraints so it may be a thing to be on the lookout for since the civil site designer might not be thinking about the building's exterior subsurface needs.

 

[cvg]

probably more a result of the phreatic surface being higher than in the surrounding ground and extending below the building into the 1:1 zone. assuming the building is on a shallow foundation

 

[fattdad]

Assuming that the building is on spread footings, what would be the failure mode if the bearing soils subsequently became saturated? The effective stress would be reduced, so that's less load. Is it a question of strength? How would saturation of the subgrade make the strength reduced? I mean ALL soil strength testing is done under saturated conditions!

So, we are left with the thought that saturated soils lose strength. How's that? I mean an embankment dam doesn't turn to mud when it gets saturated. No, what happens is the soil strength loses its soil suction and the friction angle returns to the lab value. So, lower? Yes. Below design? No.

That's just rant of mine. No clue why the building is experiencing distress. Just doubt it's because of water. There's likely something else being overlooked?

f-d

ípapß gordo ainÆt no madre flaca!

 

[cvg]

some soils are known to collapse on inundation. this causes settlement. its a big problem here