中文摘要：

为了研究垫层与刚性桩相互作用破坏机理，通过钢化玻璃模型箱进行了刚性桩复合地基模型试验，利用先进的数字照相量测技术处理桩顶垫层土体颗粒的变形场，对在加载过程中垫层土体颗粒的位移场进行全面观测与分析，并且开发二维离散元方法颗粒流程序对刚性桩复合地基垫层破坏机理进行了模拟，将数值分析结果与室内模型试验结果进行了对比；根据模型试验与数值模拟结果提出了刚性桩复合地基垫层土体的破坏模式，利用塑性平衡理论推导出垫层破坏时桩顶应力、桩间土应力及桩土应力比的求解公式，并将理论公式求解结果与试验数据进行了对比。结果表明：桩顶应力的理论计算值与试验数据吻合较好，可满足工程精度要求；垫层破坏模式的建立对于刚性桩复合地基垫层受力机理的揭示具有一定参考价值。

英文摘要：

In order to study the failure mechanism of interaction between cushion and rigid pile, model tests on rigid pile composite foundation were carried out in a tempered glass box. The digital photogrammetry was used to investigate the deformation field of soil particles in cushion at the top of pile. The displacement field of soil particles in cushion was observed and analyzed globally during the loading procedure. Particle flow code of two-dimensional discrete element method was developed to simulate the failure mechanism of cushion in rigid pile composite foundation. Numerical analysis results were compared with the experimental results. The failure mode of the cushion soil was put forward, according to the results of model test and numerical simulation. Based on plastic equilibrium theory, a formula to solve the stress of pile top, soil between piles and pile-soil stress ratio was derived when the cushion failed. The theoretical results calculated by the formula were compared with the test data. The results show that thetheoretical calculation meet the engineering results of the stress of pile top agree well with the test data, which can requirement of accuracy. The establishment of cushion failure mode is helpful to reveal the bearing mechanism of cushion in rigid pile composite foundation.