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置换率是确定CFG桩复合地基的关键指标之一,根据土层分布明确桩长后针对目标附加荷载选择置换率是竖向结构体系决策的基础,目前缺少不同置换率复合地基力学性状附加荷载影响规律共同认知。通过进行2组相同附加荷载和加固深度、不同置换率的复合地基离心模型试验,研究复合地基桩身轴力、桩侧摩阻力、桩土应力比和地基沉降响应附加荷载的分布及变化规律。研究结果表明,因置换率的增大,(1)CFG桩所承受的轴力有所减小,且轴力最大值所在位置上移;(2)摩阻力零点位置和桩体上部负摩阻力最大值位置出现上移且后者变化速率加快,桩端最大正摩阻力值明显减小;(3)桩土应力比有所减小,且在深层土体中其沿深度方向的减小速率变小;(4)地基沉降和地表沉降明显减小,地表沉降与荷载呈线性关系变化,CFG复合地基的复合模量有所提高。
The replacement rate is one of the key indexes to determine the CFG pile composite foundation. Choosing the replacement ratio for the target additional load according to the soil length distribution clearly is the basis for the decision-making of the vertical structural system. At present, the influence of the additional load on the mechanical properties of the composite foundation with different replacement ratios Common law of cognition. Through two sets of centrifugal test of composite foundation with the same additional load, depth of reinforcement and different displacement ratios, the distribution and variation of axial load, lateral friction, pile-soil stress ratio and additional load of foundation settlement response are studied. The results show that due to the increase of displacement rate, (1) the axial force of the CFG pile decreases and the axial maximum force moves upward; (2) the zero point position of the friction resistance and the negative friction force of the upper part of the pile (3) The stress ratio of pile-soil decreases, and in the deep soil, the rate of decrease along the depth direction (4) The settlement of foundation and the settlement of ground surface obviously decrease, and the linear relationship between settlement and load changes. The composite modulus of CFG composite foundation is increased.