能量桩群桩工作特性简化分析方法研究

A simplified method for geotechnical analysis of energy pile groups

采用双曲线模型模拟桩土界面上的力学行为,利用剪切位移法反映剪应力在土层中的传递,考虑群桩之间的相互作用,建立了热-力耦合作用下能量桩群桩基础工作特性的简化分析方法。该方法能反映桩土界面上的非线性、桩顶的约束条件和能量桩位置的影响,可直接计算所有桩的位移和轴力。与现有方法相比,计算得到的双桩相互作用因子更加合理。通过与文献中试验数据的对比表明,若只有局部桩经历温度变化,能量桩运行过程中各桩之间存在差异变形,基础出现倾斜,桩顶荷载发生重分布。所建立方法计算方便,能合理模拟能量桩群桩基础的主要工作特性,可用于大规模能量桩群桩基础的设计计算。

A simplified analytical method is proposed for the geotechnical analysis of energy pile groups under thermo-mechanical loads. The relationship between the shear stress and the relative displacement at the pile-soil interface is modeled by a hyperbolic function. The elastic shear displacement method is used to determine the deformation of the surrounding soil. Assuming the settlements induced by the adjacent piles are elastic, the shaft and base interactions among piles are considered separately. The effects of the nonlinear behavior at the pile-soil interface, the pile head restraint condition, and the location of energy piles in the pile group can be predicted reasonably. The computed interaction factor between two energy piles by the proposed method are better than those from the elastic approach. The reliability of the present method is also validated with the experimental data collected from literatures. Both the computed and the measured results show that if part of the piles are subjected to the temperature change, the foundation tilting and the redistribution of the axial load among the piles will be induced. The present method can capture the main characteristics of energy pile groups efficiently and be used as a useful analysis tool for the engineering design.