Estimation of Normal, Inverse, and Irregular Earth Profile Using Different Global Optimization Techniques from Active MASW Survey

Multichannel Analysis of Surface Waves is a non-invasive geophysical method that is used to determine the shear wave velocity profile of soil. Most of the previous investigations claimed the suitability of various techniques to find the site representative shear wave velocity (Vs) profile. Different soil profiles can be predicted by inversion of the dispersive nature of the fundamental mode, which represents the phase velocity and frequency. But the soil profile based on the different nature of soil stiffness has not been explored in the available research using suitable optimization techniques such as Artificial Bee Colony (ABC), Particle Swarm Optimization (PSO), Teacher Learner Based Optimization (TLBO), etc. Normally dispersive nature is more common in MASW interpretation where soil stiffness gradually increases with depth. However, interpretation problems arise in case of inverse, or irregular profiles covering a certain depth. Hence, this study focuses on such profiles to check the efficiency of various optimization techniques on dispersive nature extraction and estimation of actual Vs profile. Tests have been performed at specific sites in the IITGn campus, where the soil stratum varies significantly. The various set of initial Vs models were analyzed iteratively. The accuracy of Monte Carlo optimization is also investigated to generate a composite dispersion curve and corresponding Vs profile for each Site.