Effective stress/Overburden calculation method

[Darrensw]

I work in a UK independent soils laboratory and often receive samples from clients that want permeability, UU triaxial or shearbox tests, but the client fails to supply the effective stress details. When asked the pressures to be applied to the samples, they often don't even know they are required to specify them, let alone what they should be.

I wonder if anyone knows where I can find a published method of calculating overburden pressure and effective stress from the sample depth and can point me to a document I can use.

Thanks.
Darren

 

[BigH]

mmmmhhh - I thought this was geoengineering 101?!! Pick up any soils book and they will tell you how to calculate overburden pressure. Simplistically, Total pressure = unit weight x depth to consideration (adjust unit weight and thicknesses to stratigraphy). Know where the water table is and subtract off the pressure due to the weight of water above your point = effective pressure.