静压沉桩桩体受力全过程数值分析

Finite element analysis of pile stress in static pressure pile installation

沉桩是十分剧烈的桩-土相互作用过程,沉桩过程中桩体受力形态对桩后期承载力和耐久性有重要影响。本文运用有限单元法对静压沉桩进行数值模拟,通过位移控制法实现沉桩,模拟计算沉桩过程中桩土径向压缩和竖向摩擦,对沉桩全过程桩体受力情况进行分析。结果显示,沉桩过程中桩主要承受竖向压应力,尤其沉桩后期桩顶部受到的竖向压应力较大。采用单因素控制法对影响桩体受力的各项因素进行分析,并对各影响因素进行相关性和敏感性分析。分析表明,静压沉桩过程中桩体受力与摩擦系数、内摩擦角、粘聚力和桩尖角呈正相关,与桩径呈负相关,桩尖角对桩体所受竖向应力敏感性较弱。

The interaction process of pile-soil is severe in pile installation. In the pile installation process, pile stress conditions have an important influence on pile bearing capacity and durability. In this paper, finite element method is used to carry out numerical simulation of the pile installation process through the displacement control method. The whole process analysis of pile stress is realized with simulation calculation of pile-soil radial compression and vertical friction. The results show that pile bears vertical compressive stress mainly in the process of pile sinking. Especially, the vertical compressive stress becomes bigger in the end of pile installation. The single factor control method is used to analysis the influence of various factors on pile stress, and the correlation and sensitivity analyses are performed. Analyses show that the pile stress has a positive correlation with the friction coefficient, internal friction angle, cohesion and pile-point angle in the process of pile installation, and is negatively correlated with the pile diameter. Pile-point angle has weak sensitivity to pile stress.