Analysis on dynamic response of cast-in-place concrete thin-wall pipe pile composite foundation under lateral seismic excitation

Abstract

A new form of driven Cast-in-place Concrete thin-wall Pipe pile (referred as PCC pile) developed independently by GeoHohai has recently been patented in China. In this paper, the dynamic responses of PCC pile composite foundation under lateral seismic excitation have been analyzed with three dimensional nonlinear finite element method (3DFEM) . The soil initial stress field is computed by static calculation, in which the nonlinear elastic Duncan-Chang constitutive model has been adopted to simulate soil behavior. In dynamic calculation, the soil is considered to be Viscoelastic material and the equivalent linearization dynamic constitutive model is also applied for simulation. The viscous-elastic boundary is set along the model boundaries. According to the analyses on numerical results of absolute acceleration, relative dynamic displacement and dynamic stress, some conclusions are obtained as follows: The maximal acceleration response locates at the top of reinforced area. That in reinforced area is greater than unreinforced area. The acceleration response at the top of natural foundation is smaller than the composite foundation. The deformation of PCC pile composite foundation is smaller than solid pile composite foundation. The maximal shear stress in pile is greater than in soil. That in PCC pile is greater than in solid pile. The maximal tension stress locates nearby the depth of 1/4 to 1/3 pile length. The distribution of seismic force is changed by PCC pile composite foundation which made the reinforced area participate more seismic force. The contrastive results of several different models show that the dynamic response of PCC pile composite foundation is smaller than that of the solid pile composite foundation with the same cross section to PCC pile, which indicates that the PCC pile composite foundation is more effectively anti-seismic. © 2008 Science Press Beijing and Springer-Verlag GmbH Berlin Heidelberg Geotechnical Engineering for Disaster Mitigation and Rehabilitation.