Ground response analysis and liquefaction hazard assessment for Vishakhapatnam city

Abstract

Liquefaction is a complex phenomenon where the soil is subjected to high strain levels due to dynamic loading at the time of seismic events, contributing to severe damage and collapse of the structures. The effect of liquefaction can be predicted in three stages, i.e., evaluation of susceptibility, hazard and deformations. Soil susceptibility to liquefaction can be assessed using the geotechnical properties such as grain size, age of the soil deposit, penetration resistance of the soil, whereas hazard can be assessed in terms of factor of safety estimated against liquefaction. In the present study, one-dimensional equivalent linear ground response analysis has been carried in the study area Vishakhapatnam, Andhra Pradesh (India) and the surface peak ground acceleration (PGA) has been estimated using DEEPSOIL. The surface PGA values obtained have been used in liquefaction hazard assessment using stress-based method (SBM) and energy-based method (EBM). Hazard maps were generated from the estimated values of PGA and factor of safety against liquefaction (F L). The surface PGA values obtained are in the range of 0.09–0.14 g which are higher than 0.1 g (limiting value provided by Seismic code of India (IS: 1893-2002)). It is observed that the locations in the central part of the city are prone to higher accelerations comparatively. From liquefaction potential assessment, it is evident that most of the locations in northern and central parts of the city are prone to liquefaction. As the study area has two operational ports and is highly industrialized, findings from the present study will be helpful in retrofitting, analysis and design of structures, therefore, solving practical challenges in structural and geotechnical engineering.