Exploring liquefaction susceptibility of Kutch region in Gujarat through MASW analysis: a case study

Abstract

Soil liquefaction is critical for the very loose soil deposit in the earthquake-prone area. A detailed site investigation and liquefaction analysis are necessary to construct massive structures (such as oil tanks and high-rise skyscrapers) in these soil conditions. The multichannel analysis of surface waves (MASW) technique is a non-invasive and quick test to estimate the shear wave velocity (Vs) profile. This work presents a case study of liquefaction analysis and soil site classification of the Kutch region in the state of Gujarat, India, using the MASW technique. Geophone spacing of 1.5 m with an offset distance of 15 m was used for the data acquisition. The source was activated by hammering to generate wavefields. The wavefields were recorded at the sampling frequency of 4000 Hz for a duration of 0.6 seconds at nine locations. The phase shift method was used for the dispersion analysis of these wavefields, and teaching-learning based optimization was used for the inversion analysis to estimate the Vs profile. The Kutch region was categorized as site class D (stiff soil) based on the National Earthquake Hazard Reduction Programme (NEHRP), and the predicted Vs30 values from all sites ranged from 180 to 360 m/s. The liquefaction analysis based on Vs values suggested that there was a risk of liquefaction because of loose soil layers in the top 12 m.