挤密砂桩复合地基非线性沉降的计算方法

Calculation method for nonlinear settlement of sand compaction pile composite foundation

港珠澳大桥工程是国内首次大规模采用高置换率挤密砂桩复合地基的工程,该复合地基的沉降变形计算方法经验性较强,计算结果往往差异较大,因此进行承压板边长为5.4 m的大型复合地基荷载试验以验证设计参数。采用双曲线模型对该荷载试验的荷载-沉降曲线进行拟合,建立考虑地基非线性变形的切线模量与附加应力之间的关系,验证切线模量法沉降计算方法的可行性。同时分别采用该方法和规范方法对复合地基在主体结构荷载作用下的地基沉降进行计算对比。结果表明,采用考虑地基非线性变形的切线模量法计算结果更接近实测值。

For the first time in China, the high replacement rate sand pile composite foundation is widely used in Hong Kong-Zhuhai-Macao Bridge project. The settlement deformation calculation method of the composite foundation is empirical, and the calculation results are often different. Therefore, we carry out the load test of a large composite foundation with a bearing plate side length of 5.4 m to verify the design parameters. We apply the hyperbolic model to fit the load-settlement curve of the load test, establish the relationship between the tangent modulus and the additional stress considering the nonlinear deformation of the foundation, verify the feasibility of the settlement calculation method of the tangent modulus method, and calculate and contrast the settlements of composite foundation under the main structure load by this method and the standard method respectively. The results show that the calculation result of the tangent modulus method considering the nonlinear deformation of the foundation is more consistent with the measured value.