Vesic Method using total vs effective stress

[DTS419]

When using the Vesic Method for calculating bearing pressure, is it more appropriate to use effective stress or total stress? I have some lab measured data for a soil where the lab reported both phi and cohesion for the soil samples, but I get varying results depending on which I use. The total stress data gives very small values for phi with cohesion values ranging from 800-1000 psf whereas the effective stress data gives cohesion = 0 and values for phi in the 20s.

 

[EireChch]

I think you need to contact a geotech, you need someone who knows the local material and how to interp lab testing. Its not a case of which is more appropriate. You need to do both. When you work with a material and know it well you can generally know which case dictates