目前关于格栅状搅拌桩复合地基工作性状的研究工作相对较少,对其变形机理不甚了解。在兴隆水利枢纽格栅状搅拌桩复合地基现场载荷试验成果的基础上,考虑桩-土之间的相互接触,建立考虑搅拌桩-土共同作用的三维有限元模型,数值模拟复合地基群桩现场试验的实际加载过程。通过对比口字型群桩试验与数值模拟的P-S曲线,验证了数值方法及参数取值的正确性;分析了桩身轴力、桩间土的竖向应力及桩侧摩阻力等变化规律,研究了桩体与土体的荷载分担过程关系,获得桩身轴力及摩阻力分布规律;根据竖向平衡方程,推导得到平均桩端阻力和侧阻力,研究可为工程设计提供参考。

Currently there are relatively few studies on the work traits of grille-structured composite foundation composed of cement mixing piles, and its deformation mechanism is not clear. On the basis of field load test results of grille-structured cement mixing pile composite foundation in Xinglong hydropower project, a three-dimensional finite element model which could reflect the mechanics of interaction between soils and piles was established by considering the contact action between soils and piles. The actual loading process of field test of composite foundation’s pile group was simulated using this model. Through comparison of the P-S curve between grille-shaped pile group tests and numerical simulations, the correctness of the numerical model and parameters are verified. Furthermore, the variation regularities of pile’s axial force, vertical stress of soils among piles, and pile’s lateral friction were analyzed. The time course of load sharing relationship between piles and soils is studied, and the distribution of axial force and friction of piles are acquired. According to the vertical balance equation, the average tip resistance and lateral resistance can be calculated by numerical analysis.