ABSTRACT
The conventional concept of effective stress of Terzaghi as the pivotal concept in soil mechanics applied in quantifying shear strength and settlement is elaborated with the various soil settlement equations introduced. The complexity involved in characterising the soil settlement driven by effective stress decrease like in wetting collapse, which contradicts the concept of effective stress, is highlighted. This is the point where researchers are trying to incorporate strength in the soil volume change model. Various soil complex settlement behaviours, which cannot be explained by the conventional effective stress concept, are described to indicate the complexities involved in the formation of soil volume change framework. Then the detail derivation of the non-linear failure and mobilised shear strength envelopes of Md Noor and Anderson at various axial strains are explained. The concept of effective stress and shear strength interaction, which is being derived from the anisotropic compression behaviour in soil triaxial specimen, is explained. The effective stress is represented by a Mohr circle and the mobilised shear strength is represented by the non-linear mobilised strength envelope. The role of a steep drop in shear strength relative to suction governing the massive soil settlement near saturation during wetting is demonstrated using a three-dimensional conceptual model.
