Static liquefaction and effective stress path response of Kutch soils

The current research is focused on the static liquefaction and effective stress path characteristics of soils of the high seismicity Kutch region, India. In previous studies, the effects of the fines content and the plasticity of the fines on the undrained behavior were explored in a controlled and systematic manner with either non-plastic or plastic fines added to standard or river sands. The undrained characteristics of natural soil deposits having the simultaneous presence of both silt and clay fractions have not been explored. In the present study, the effects of a varying fines content and the nature of the fines on the static liquefaction and effective stress path characteristics of various soil deposits in the Kutch region at their in-situ densities have been studied. Various liquefaction indices were determined to quantify the static liquefaction, namely, the undrained brittleness index, the collapse potential, the liquefaction potential, and the resistance to further deformation. The variation in these parameters was analyzed in the context of the fines content, silt content, clay content, and plasticity. The effective stress paths of the Kutch soils exhibited a strain softening, limited strain softening or strain hardening response and their behavior was controlled by the fines content and its nature. Due to the presence of non-plastic fines, and irrespective of the content, the silty sands exhibited intense strain softening which was captured by the liquefaction indices.