STRENGTH OF COHESIVE SOILS

Abstract

1. Strength of cohesive soils cannot be explained in terms of clear cut parameters, as it depends on various factors which are inter:-dependent. Efforts have been made by different research workers to explore important individual factors such as, soil type and structure, time effect (creep and relaxation), influence of intermediate principal stress, influence of anisotropy, dilatency effect, progressive failure process, influence of disturbance in sampling, scale effect of specimen, etc. In clays adsorbed water layer plays an important role, Their grain constituent, she and structural arrangement give soils compressibility and resilience. Because of low permeability they retain neutral stresses for a long time. The various passible effects of adsorbed water, compressibility, neutral stresses and low permeability provide clays with ,*t" most unlimited variations in shear strength. 2. For the simplified assumption of plane strain, the yield criteria (i.e., the relation existing between the stresses at the limiting condition) combined with the two equations of motion renders the problem statically determinate. But the difficulty is to determine the mathematical nature of the failure criterion that prevails for soils. The two approaches viz., the tacit assumption of an yield criterion, and the failure criteria based on test results have their own limitations. 3. All studies of cohesive soils sheared to failure present empirical relationship between the various factors at failure whose numerical values hold only for the soil or soils tested.