Bearing pressure reduction due to water level 1

[struct_eeyore]

Hi all,

We will ultimately be subcontracting a geotech to answer this question, but I am in the need of some rough number to start sizing a foundation. I have a retaining wall that will be lining a side of a boat ramp which projects into a river. Cantilevered design - the footer shall be about 2-3' below the surface and protected from scour/erosion. A previous geotech report near the site called out granular soils w/ 2000psf bearing capacity. For the initial sizing, how much should I reduce my bearing capacity assuming the footer will be anywhere from 12' to 13' below the water level.

 

[MTNClimber]

2000 psf is pretty low for sands but may be appropriate if the density is loose. Do you know the density of the material listed in that report?

 

[oldestguy]

If this wall will carry backfill, such as 12 ft. or more I'd look into the pressures from the backfill as to submerged density, etc. and effect of any water level changes with time. Placing fill in water is different than doing so above the water level.