Effective strength parameters for clay

[tipsabc]

I am trying to get the effective strength parameter for clay. If I know the SPT number and undrained cohesion Cu for a normally consolidated clay, how to get the effective phi for this clay? Any reference? Thank you very much.

 

[GTeng]

Can't be done from the parameters you supplied. You can look at correlations with plasticity parameters (Holz and Kovacs, NAVFAC) but the only way to actually measure is by a triaxial compression test, either drained or undrained with pore pressure.

 

[dgillette]

Just out of idle curiosity, what do you plan to use the effective-stress parameters for? Is the clay heavily over-consolidated?

Regards,
DRG