关键词: 开孔管桩, 循环荷载, 孔压积累, 孔压消散

Abstract: Under conditions of seismic action or any other mutation stresses, the soil of the liquefiable foundation can lose its strength and stiffness rapidly due to the liquefication, resulting in the loss of the bearing capacity. The traditional anti-liquefaction measures mainly focus on the ground treatment, while the open-hole pipe pile provided in this paper has both anti-liquefaction and bearing capacity. Firstly, the liquid flow in the holes of the pipe pile is assumed to meet the Poiseuille equation, and the equal strain assumption is applied. Then we derive the analytic solution of the pore pressure considering both radial and vertical flows under the time-varying load, combined with the stress concentration phenomenon of the pipe pile composite foundation. Furthermore, considering the pore pressure accumulation under cyclic loading, the analytical solution is improved by using the empirical model of pore pressure development. Based on the analytical solution, this paper analyzes and compares the development of pore pressure of the open-hole pipe piles, gravel piles, undrained piles and natural foundation. Thus, the results indicate that the open-hole pipe pile has the best drainage capacity. The factors such as the modulus ratio of pile and soil and the radius ratio have important influence on the development of pore pressure. The higher the modulus ratio of pile and soil is, the smaller the radius ratio is, and the faster the pore pressure dissipation rate is. The influence of open-hole coefficient on the development of pore pressure is not obvious. The load frequency only affects the peak value of initial pore pressure and has little influence on the rate of pore pressure oscillation attenuation.

Key words: the open-hole pipe pile, cyclic loading, pore pressure accumulation, dissipation of pore pressure