DESIGN OF PILE FOUNDATIONS FOR EARTHQUAKE LOADS

Abstract

The response of pile foundation is complex under real earthquake motion. In analysis of design forces for pile foundation, applied motion parameter play significant role. Effect of PGA and predominant frequency plays important role in design parameters. A three-dimensional soil-pile system is numerically formulated in finite difference based software FLAC3D. For nonlinear behaviour of soil, Mohr-Coulomb model is assigned to soil media. Under dynamic loading free field boundary condition is applied to soil-pile system to absorb the reflecting waves. Effect of kinematic interaction analyzed for single pile under Bhuj (2001) earthquake motion. PGA of the applied motion significantly changes behaviour of soil –pile system due to nonlinear soil model. Spectrum compatible ground motions of Bhuj earthquake , scaled for different earthquake zones of India (viz., 0.10g, 0.16g, 0.24g and 0.36g) are used for effect of PGA. Response of pile foundation is significantly increased if the predominant frequency of exciting motion is near to fundamental frequency of soil-pile system. Pile group response is examined under increasing PGA. Behaviour is compared with single pile and found displacement slightly high in single pile and lateral shear significantly high for pile group near pilecap. Response of pile is get amplified due to consideration of superstructure.