Behavior of Marine Sand-Clay Mixtures under Static and Cyclic Triaxial Shear

In situ Indian Marine soils occur as mixtures of sand and clay in widely varying proportions. Their engineering behavior has not been comprehensively and systematically studied. An experimental program on reconstituted Indian marine soils having different proportions of sand and clay was undertaken. The study comprised one dimensional consolidation tests and static and cyclic triaxial tests. This paper presents the results of this study and offers an interpretation of the behavior based on effective void ratio (EVR), a new parameter defined as the ratio of volume of voids to the volume of effective soil fraction. Experimental results indicate a roughly unique EVR-logσvc′ relationship and normalizability of undrained static behavior. Some predictions from the stress history and normalized soil engineering properties (SHANSEP) approach with EVR as basis, in close agreement with experimental data, have been presented. Hence EVR is proposed as an appropriate parameter for describing and predicting the behavior of sand-clay mixtures. The development of pore pressures and strains during cyclic loading is dictated by a combination of EVR and cyclic stress ratio for sandy clays and by a combination of void ratio and cyclic stress ratio for clayey sands.