基于球孔扩张理论和侧阻力退化效应的压桩力计算模拟

根据静压桩的贯入机制，将沉桩过程模拟为半无限土体中一系列球形孔的连续扩张，土体假定为Mohr-Coulomb材料。利用球孔扩张和源-源假设理论，并采用Boussinesq解进行地面应力的修正，在此基础上分别计算出桩侧极限摩阻力和桩端阻力。通过现场试验研究发现，沉桩过程中侧摩阻力退化效应带来的影响是明显的，提出了相应的侧阻力退化公式。在充分考虑以上因素的基础上推导出了静压桩压桩力的模拟计算公式。使用Matlab6.5软件进行理论计算，并与山西太原某试验进行对比分析，一定深度以下理论值与实测数据基本吻合，证明该计算模拟是可行的。

Computational simulation of jacking force based on spherical cavity expansion theory and friction fatigue effect

According to penetration mechanism of jacked pile, the expansion of a series of spherical cavities in semi-infinite space is used to simulate the process of pile installation; and soil is assumed as Mohr-Coulomb material. By using the theory of spherical cavity expansion, imaging method and Boussinesq solution, the surface stresses is corrected; then ultimate frictional resistance and end-bearing capacity can be confirmed respectively. The data from field test show that the effect of friction fatigue during installation is obvious; and the relevant formula of friction fatigue is presented; then the computation formula is deduced based on the factors above. It is proved that this method is feasible because the values calculated by the presented formula with software Matlab6.5 are consistent with the field test results in Taiyuan of Shanxi Province under given depth.