竖向荷载下挤扩支盘桩数值模拟计算与分析

结合挤扩支盘桩和土体的实际参数,基于Marc有限元软件,采用六面体单元模拟挤扩支盘桩和桩周土体,建立了桩-土相互作用的三维空间模型,分析了竖向荷载作用下挤扩支盘桩和桩周土体的位移变化规律、桩身轴力传递规律及支盘端承力的变化规律,并与同直径等截面桩的极限承载力进行了对比.研究结果表明:在竖向荷载的作用下,桩顶的位移最大,离桩越远,土体的水平位移越小；桩身轴力在支盘处的变化较大,支盘承受了大部分荷载；各支盘端承力不能平均分配,应充分考虑各个支盘的位置和支盘端土体的力学特性,设计合理的支盘间距,才能最大限度地提高支盘桩的承载能力；挤扩支盘桩的极限承载力约为同直径等截面桩的2倍.

Numerical simulation on the squeezed branch pile under vertical load

Combined with actual parameters of a squeezed branch pile and its surrounding soil,based on the finite element software Marc,hexahedron elements were used to simulate the squeezed branch pile and its surrounding soil,and a three dimension spatial model of pile-soil interaction was established,the displacement variation law of the squeezed branch pile and its surrounding soil,the axial force transfer mechanism of pile shaft and the bearing capacity variation law of the plate end were analyzed under the vertical load,and the ultimate bearing capacity was contrasted between the pile and the uniform cross-section pile with the same diameter.The results show that the maximum displacement was in the top of the pile,the horizontal displacement was smaller when the piles were put farther away from each other,the axial force of pile shaft changed greatly in the plate with most load of the plate beard.Bearing capacity could not distribute equally,full consideration should be given to the position of each plate with the mechanical properties of soil near the plate end,the bearing capacity of the squeezed branch pile could be largely improved for a reasonable plate space,the ultimate bearing capacity of the squeezed branch pile was about two times as much as the uniform cross-section pile with the same diameter.