Pore pressure characteristics of normal and over-consolidated clays

The pore pressure u in undrained triaxial compression tests was normalized with equivalent consolidation pressure p′e of the Hvorslev Strength Theory.A bi-linear relationship between u/p′e and stress ratio η was validated for isotropical over-consolidated clays.A linear relationship passing through the origin of coordinates between u/p′e and η was fitted well for the normally consolidated clays.The coefficient C is related with the friction angle in failure.The formulation of the pore pressure coefficient was deduced by the use of the linear relationship.The predicted pore pressure coefficients varying with η agree well with those predicted by the pore pressure formulation deduced from the Cam-clay Model.