THREE-DIMENSIONAL ANALYSIS OF SOIL-PILE-STRUCTURE INTERACTION PROBLEM ON HIGH RISE BUILDING ON IMPROVED SOFT SOIL

Abstract

This study presents the numerical simulation of flexible wall barrel soil-pile-structure interaction analysis. Soil-Structure Interaction (SSI) is usually assumed beneficial during an earthquake. However, SSI can also increase permanent deformation and decrease the stiffness of the pile foundation system which affects seismic response and displacement in the overall structure, especially high-rise buildings. Non-linear 3D FEM models with a gap/slap mechanism have been developed in ABAQUS to simulate the effect of soil-pile-structure interaction (SPSI). The objectives of this research are to study the effect of SPSI on soil response, kinematic properties of the superstructure, and the modeling of SPSI problem with the superstructure, and to increase horizontal stiffness of foundation system by using the cement-mixing method. The analyses in this study include superstructure analysis with fix-based, SPSI, and SPSI with cement-mixing. The constitutive models in this study are Mohr-Coulomb for soil material and Linear-elastic for the upper structure. The calibration of the flexible wall barrel modeling technique was successfully calibrated with a shaking table reference case with some variation of the results. It is observed that SPSI provides flexibility and damping to the superstructure. The gap/slap mechanism is clearly observed on the contact surfaces between soil and superstructure at a shallow level. Cement-mixing soil improvement increases horizontal stiffness resulting in a stiffer response of superstructure and reduction of pile stress during earthquakes. The influence of SPSI on superstructure and comparisons between simulation cases are then discussed. However, this study does not consider consolidation and the contraction properties have been simplified.