Numerical modeling of connected piled raft foundation under seismic loading in layered soils

Abstract

AbstractUntil recently, the behavior of connected piled raft foundation was not fully understood in the seismically active region due to the complex dynamic soil–pile–foundation structure interaction. This concern arises when the soil deposit-supported foundations are stratified or heterogynous and subjected to high ground motion intensity. In the current study, a series of numerical analyses using ABAQUS software have been conducted on a pile group of (3 × 3) arranged into a square pattern to investigate the seismic response of piled foundations embedded in dry sandy soil (homogenous and layered), and how the amplification of propagated waves affects the bending moment along piles. For mesh generation, an artificial boundary condition using the tied-nodes approach was adopted to simulate the free-field motion of soil under earthquake excitation. The structure used a single degree of freedom with a lumped mass. Moreover, Mohr–Coulomb and linear elastic models have been chosen for soil and pile–raft, respectively. The results demonstrate that the foundation rocking increases in stratified soil compared to homogenous soil, irrespective of the seismic intensity. The maximum bending moment was observed at the pile head in homogenous soil and shallow depths in layered soil because of the kinematic interaction at the soil interface. The results also indicated that the amplification factor (acceleration at a certain depth to the acceleration at bedrock) was found to be 203 and 189% in homogenous soil for PGA values of 0.1 and 0.33 g, respectively. Almost there were no effects of seismic intensity in layered soil on the amplified waves transmitted into the soil surface.