Probabilistic Models for Uncertainty Quantification of Soil Properties on Site Response Analysis

The geotechnical properties of soil deposit and the variability associated with their probable distributions have a profound impact on the seismic response of a site. In the present work, the influences of soil profile characterizations corresponding to the shear wave velocity (Vs), density, and material degradation using various probabilistic distributions are investigated. A stochastic process is introduced for solving the spatial variability in soil deposit via Monte Carlo simulations. The results are validated with those obtained from the reference solution using the Strata program version 0.5.5. Additionally, sensitivity analysis is conducted to investigate the effect of the random input variables in the soil profile. The analysis concludes that the consideration of probabilistic distributions of the geotechnical parameters plays a significant role in evaluating the reliability of a site. The variability in material degradation has a greater impact than the unit weight on site response. Furthermore, comparatively the variability in Vs for both the Toro model and log-normal distribution is identical for periods greater than 1.0 s, while in the range of lower periods, the former is lower than the latter with maximum reductions of 11.14% and 20.86% in surface response spectra and amplification factor, respectively.