基于颗粒流的基桩自平衡测试法数值模拟

为了揭示基桩自平衡测试法在加载过程中单桩的承载特性以及桩土相互作用规律,基于二维离散元软件PFC^2D模拟工程实践中基桩自平衡测试法的加载过程,分析单桩在受荷条件下的模拟试验。研究结果表明:①在加载初始阶段,桩侧阻力要优于桩端阻力发挥,但是桩端阻力也有一定的发挥,随着加载的进行,桩端阻力开始占据一定的作用;②在加载过程中,桩周土体孔隙率呈有规律的变化,具体表现为桩端一定范围内的土体孔隙率减小,且越靠近桩端,孔隙率变化越大,沿竖直方向变化趋势减小,桩侧土体孔隙率的变化则主要是荷载箱附近和上段桩上部一定范围内增大;③在加载过程中,随着荷载的增大,桩周土体颗粒之间的配位数,土体水平向应力、竖直向应力以及桩周土颗粒的位移均呈有规律的变化。研究结果可为自平衡测试法的理论研究提供参考。

Numerical Simulation on Self-Balance Test of Foundation Pile with PFC2D

In the aim of revealing the bearing behavior of single pile and the interaction between pile and soil in self-balanced test of foundation pile, DEM software PFC^2D is employed to simulate the loading process in the self-balanced test.Test results reveal that: (1) in the initial stage of loading, side resistance of pile was superior to tip resistance which had also some play, but tip resistance occupied a certain role with the increase of load. (2)The porosity of soil surrounding pile changed regularly in the process of loading.Within a certain scope of pile tip, soil porosity decreased, and the closer to the pile tip, the greater porosity changed; in the adjacent of load cell and upper section of pile, soil porosity increased.(3) The coordination number between soil particles, the horizontal soil stress and vertical stress, as well as the displacement of soil particles surrounding pile changed regularly with the increase of load. The research results would offer support for the theoretical study on self-balanced test of pile.