muddy soil bearing capacity

[AskTooMuch]

When soil is muddy after a rain it is softer. When you walk on muddy soil, your shoes/feet sinks more than when soil is dry.

But when you check a footing and consider water buoyancy (water table is near surface) water actually "helps" when checking the soil bearing check vs vertical downward loads.

Anyone got a good clarification on this. This makes me wonder and can't find a good explanation/reasoning.

 

[JStephen]

I think the geotechnical engineer has already considered the reduction for wet soil when he gives you the allowable soil bearing, and there might be considerably more strength available in dry conditions, depending on the soil types.

 

[Settingsun]

The rule of thumb I've seen is to halve bearing capacity when water is near or above foundation level. Alternatively, you can consider it directly in the bearing capacity calculation by taking buoyant weight of the soil.

Benefit from reducing load would be minimal for typical buildings as the load comes from above water level.