Modeling of the Seismic Response of the Aggregate Pier Foundation System

There are a lot of ground improvement techniques that have been developed. One of them is the aggregate pier foundation system. The response of an aggregate pier foundation system during seismic loading was investigated. Comprehensive numerical modeling using FLAC were performed. The research was divided into three parts: 1) ground acceleration, 2) excess pore water pressure ratio, and 3) shear stress distribution in the soil matrix generated during seismic loading. Two earthquake time histories scaled to different maximum acceleration (pga) were used in the numerical modeling: the 1989 Loma Prieta earthquake (pga = 0.45g) and the 1988 Saguenay earthquake (pga = 0.05g). The results of the simulation showed that: 1) the aggregate pier amplifies the peak horizontal acceleration on the ground surface (a_max), 2) the aggregate pier reduces the liquefaction potential up to depth where it is installed, 3) pore pressures are generally lower for soils reinforced with aggregate pier than unreinforced soils, except when the applied shear stresses exceed the cyclic shear resistance of the aggregate materials, and 4) the maximum shear stresses in soil are much smaller for reinforced soils than unreinforced soils.