Bearing Pressure Tests

[aj3006]

Help! Trying to get a design sorted for a deadman and have been advised by my civil engineers that they are unable to determine ground bearing capacity from the the GI report supplied by the client, in which Undrained Shear Strength Tests in Tri-axial Compression are contained.

Is there some way of determining Bearing Capacity from these figures?

 

[Ron]

Bearing capacity won't likely control your deadman design. First, the deadman won't likely exert much vertical load, relative to the bearing capacity. The deadman will be controlled by dead load, corresponding sliding friction, and the failure of the wedge of soil that will be pushed when the deadman is mobilized.

But to answer your basic question...you do not have enough information to determine the bearing capacity.

 

[BigH]

Sorry - but if you have undrained shear strengths for cohesive soil and you have cohesive soil, you can certainly determine allowable bearing capacity (ultimate with a safety factor). However, Ron is correct, in that they are probably asking for the lateral capacity of the deadman - horizontal direction which is basically the passive pressure in front of the deadman. This is likely low - so I might suggest that in front of the deadman, you replace the soil (within the passive zone) with good granular soil so that the passive resistance is determined by the imported material - i.e., the potential rupture surface is contained within. You might wish to check out Bowles 5th edition - he has several pages on the design of deadman anchors.