Developing a Region-Specific Predictive Model for Shear Wave Velocity to Evaluate Seismic Site Response and Liquefaction Potential of Silty Soils

Abstract

The research work explored empirical relationships between shear wave velocity (Vs) and other in-situ test results, formulating a predictive model to estimate Vs from fundamental soil characteristics. Undisturbed soil samples were collected from 5 sites in Rivers State, Nigeria and tested for index properties including liquid limit, plastic limit, and specific gravity. Direct Vs measurements were made using downhole tests. An empirical correlation model was formulated relating Vs to shear modulus, bulk density, and depth, achieving an R2 of 0.963. The soils were classified as low plasticity silts and silty clays, with liquid limits of 26.9–31.1%, plasticity indexes of 8.2–9.3%, and specific gravities averaging 2.67. Undrained shear strengths varied from 10.8–16.3 kPa with effective friction angles of 25–32 degrees. The developed Vs predictive model correlated well with NEHRP site classifications, providing insight into seismic site response. Liquefaction triggering analysis using the Vs data indicated Sites S1-S3 are susceptible, while Sites S4-S5 are relatively resistant. The study addresses the challenge of accurately estimating Vs for liquefaction assessment of complex silty soils, by developing a region-specific predictive model based on fundamental soil properties. This fills a key knowledge gap for the Niger Delta region, providing a useful framework for geotechnical site characterization and hazard mitigation in similar environments vulnerable to seismic risks. The robust Vs model and comprehensive soil data offer valuable insights for understanding the dynamic behavior and liquefaction susceptibility of these soils.