敞口管型桩压入对既有受荷桩基承载性状影响

基于经典桩侧摩阻力公式和圆孔扩张理论，优化考虑土压力系数、土塞增长率、扩孔塑性半径等问题，计算新增管桩的植入对在役桩承载性状的影响. 对比分析有限元的软件与理论计算结果，发现管型桩贯入引致的桩间土挤土效应，使在役桩侧摩阻力在一定深度范围内增加，且桩长越长、桩间距越小，贡献越明显. 新增桩与在役桩的距离小于3倍桩径，会形成局部群桩效应，使群桩协同工作时的桩顶沉降增加；距离大于6倍桩径，管型桩压入对既有桩侧摩阻力、群桩协同工作效应的影响较小.

Influence of jacking open-ended tubular piles on bearing behavior of existing in-service piles

Based on the classical pile side resistance formula and the round hole expansion theory, the effect of the implantation of new pipe piles on the bearing characteristics of in-service pile was calculated by considering the soil pressure coefficient, the growth rate of the soil plug, the plastic radius of the expansion hole and so on. Comparing the software and theoretical calculation results of finite factors, the effect of inter-pile soil extrusion caused by pipe piles is induced, so that the resistance on the side of the serving pile increases in a certain depth range, and the longer the pile length and the smaller the pile spacing, the more obvious the contribution is. The distance between the new pile and the in-service pile is less than 3 times the pile diameter, a local pile effect is formed so that the settlement of the top of the pile increases, when the pile works together. The distance is greater than 6 times the pile diameter, and the pressure of the pipe pile will has less effect on the existing pile side resistance and the group pile co-operation effect.