INFLUENCE OF SEISMIC POREWATER PRESSURE INCREASE AND LIQUEFACTION ON SITE RESPONSE ANALYSIS

Seismic site response analysis is a technique used to predict the ground’s response to local
soil conditions. Recent advancements in understanding the generation of shear-induced excess
pore pressure have led to the development and implementation of pore pressure response
models in site response analysis that take effective stress into consideration. This research
focuses on developing recent approaches to calculate site response analysis using the nonlinear
effective stress method.
The research specifically examines the impact of Porewater Pressure (PWP) buildup, soil
softening, potential liquefaction, and post-liquefaction effects on site response. The study
is divided into two stages: (1) The performance of a Porewater pressure generation model
coupled with constitutive models is tested to compute stress-strain response during shaking
using effective stresses, and to solve dynamic site response problems. (2) A parametric study
using 2D elements is conducted to determine the principal variables that affect site response
analysis.
In the first stage, the study evaluates the performance of nonlinear effective stress constitutive
models, commonly known as advanced constitutive models, used in one-dimensional
(1D) site response analysis for assessing stress-strain behavior, porewater generation, and
liquefaction potential in soft soil deposits at the element level. Three constitutive models are
combined with the porewater pressure generation model to develop coupled models called
PDMY 02, PM4SAND, and PDMY 03. The study also proposes protocols for selecting
model input parameters.