Evaluation of Liquefaction Susceptibility of Soils in Kerala, India, Based on Equivalent N Value and Equivalent Acceleration

Liquefaction of soil is one of the important concerns for the geotechnical investigators, as it leads to major casualties after natural disasters like earthquakes. Potential of liquefaction mainly depends on the soil type and the magnitude of earthquake. Developing a liquefaction susceptibility map is one of the essential steps in disaster preparedness and this study proposed a novel framework for developing liquefaction susceptibility maps by correlating the soil investigation data with equivalent acceleration obtained using the site response analysis. The usefulness of the method is demonstrated by developing the liquefaction susceptibility map of soils across state of Kerala, India. In this approach, first the standard penetration test (SPT) N values of soil from a specific location was subjected to a correction corresponding to the fine content and plasticity index of the soil, to get the equivalent N value. Then, the equivalent acceleration was analysed through site response analysis using ProShake 2.0 software for a peak acceleration of 0.16 × g. The obtained results were corrected for a wave correction to scale down the earthquake magnitude corresponding to the study area. Subsequently, the point corresponds to equivalent N value and equivalent acceleration was superimposed with the universal reference liquefaction chart proposed by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) Japan to identify the zone of liquefaction susceptibility of the study area. The method is validated with different case histories from Kerala and extended to different soil types across the state.