Geotechnical and Geophysical Characterization of Vadodara Region, Gujarat, India

Abstract

Subsurface geology and geotechnical properties play a significant role for the amplification of ground motion at the time of seismic events. Shear wave velocity model is a necessary input for the site characterization of any region. In this study, geophysical investigations in reference to multichannel analysis of surface wave (MASW) and seismic refraction tests have been carried out at 64 places in Vadodara city. The investigations were performed in the study region by dividing the whole region into 2 × 2 km grid size. SeisImager software is used to determine the shear wave velocities (Vs) and compressional wave velocities (Vp) at various depths. Around 430 borehole data have been synthesized to prepare soil profiles which include the information such as soil type, SPT-N value with depth, and water table. The soil profile of the Vadodara region is alluvium soil with loose sediments. The soil layers observed at different depths mainly consist of silty sand, silty clay, silt of low to high plasticity, clay of low to medium plasticity. Shear wave velocity and compressional wave velocity models have been generated at 5, 10, 15, 20, 25, and 30 m depth through ArcGIS software. The classification of the substrata based on the shear wave velocity profile at 30 m depth (Vs30) has been made by using soil characterization. The obtained output from the study will be used for further studies such as liquefaction assessment, seismic hazard, and risk model of the study region.KeywordsShear wave velocityCompressional wave velocityStandard penetration test number