层状地基静力压桩过程数值模拟

Numerical Simulation of Static Piling Process in Layered Soils

在分析静力压桩过程的作用机理和数值模拟关键力学问题的基础上,选用某实际工程的层状地基条件,建立单根预应力高强混凝土管桩压桩过程的有限元分析模型,进行层状地基条件下桩周挤土压力和水平位移的数值分析,并与平面应变条件下圆孔扩张解析法比较。数值分析结果表明,层状地基条件下,桩周土弹性区水平位移受深度效应和土层性质影响不明显;同一土层的桩周径向压力均随深度增加而增大;在软硬土层交界处,桩端接近硬层底时桩周压力显著减小,桩端接近软层底时桩周压力显著增大;平面应变条件下,应用圆孔扩张法求解浅层地基弹性区土体水平位移时计算结果偏大,求解桩周压力时计算结果显著偏小。

Based on the mechanism of static piling process and the mechanical theory with respect to numerical simulation, the FEM model of static piling process of single prestressed high strength concrete pipe pile in layered soils was established. According to the above FEM model, the numerical solution of pilesurrounding pressure and horizontal displacement under the condition of actual layered soils were studied. The numerical results indicate that the horizontal displacement in the elastic region around the pile is only influenced slightly by the depth and property of soils; the expansion pressure in the same soils increases with depth as a whole and, near the interface of soft and hard soils, decreases significantly when the pile tip approaching the bottom of hard soils, and increase significantly when the pile tip approach the bottom of soft soils. Compared the above numerical solution with the analytical solution with cavity expansion method under plane strain condition, it is found that the horizontal displacement in the elastic region of shallow buried soils with analytical method is bigger than that with numerical method, and the pile-surrounding pressure with analytical method is much smaller than that with numerical method.