中文摘要：

带褥垫层桩体复合地基，在荷载作用下桩会向褥垫层刺入，且在桩侧上部产生负摩阻力。针对复合地基中桩-土间存在相对滑移以及桩、土之间相互作用特性，引入Boussinesq解和Mindlin解改进基桩弹塑性分析法，并分别以双折线和双曲线函数模拟桩侧与土以及桩端与土接触面的非线性荷载传递关系，通过构建以桩、土结点位移为未知量的矩阵方程组来计算桩体复合地基沉降，同时可得到复合地基复杂的应力和位移分布规律。通过与室内模型试验和工程实测结果对比分析发现，本文方法计算结果与现场实测和室内试验结果比较一致，这证明了本文方法的可靠性。

英文摘要：

In a pile-soil composite foundation with cushion, the pile would penetrate into the cushion during loading, and a negative friction resistance usually existed along the lateral interface of upper part of the pile. Based on the feature of relative slipping and mutual reaction between pile and soil that frequently occured in composite foundations, the elasto-plastic analysis method was improved by absorbing the Boussinesqs and Mindlins solutions. More-over the nonlinear characteristics of the interface between pile and soil were simulated by use of with the double fold lines model and the double curves model, respectively. The settlement of the pile-soil composite foundations was calculated by creating and solving the matrix equations regarding the node displacements of the pile and soil as unknown quantities, at the same time, the complicated distribution of stress and strain could be obtained. By comparing the calculated results of this paper with the results of the indoor model tests and the practical engineering project, the proposed method was proved to be reliable.