大面积堆载作用下轴向受力隔离桩的承载机制分析

 为分析大面积堆载作用下轴向受荷隔离桩的被动受力特性，首先从布辛奈斯克(Boussinesq)改进解出发，推导出各种形式堆载作用下水平附加压力的理论计算公式；在此公式基础上，从土体的运动和应力的传递方式入手，对考虑土拱效应的局部塑性变形理论进行改进，从而得到合理的隔离桩桩身被动荷载分布；最后，根据考虑土体局部塑性屈服及轴向荷载重力二阶效应影响的三参数Winkler弹性地基梁模型，建立桩身弹性段与塑性段的微分方程组，求解过程中采用矩阵传递法结合Laplace正逆变换的方法解得隔离桩桩身被动受力特性的数值解，并用试验数据进行验证。结果表明，数值解与模型试验实测值吻合较好，本研究中关于被动桩的求解方法具有较高的应用与参考价值。

ANALYSIS OF BEARING MECHANISM OF AXIALLY LOADED ISOLATION PILES UNDER LARGE-SCALE SURCHARGE LOADING

This paper aims at analyzing the passive mechanical characteristics of axially loaded isolation piles under large-scale surcharge loading. Firstly，the formulation for calculating lateral additional pressure with local surcharge is deduced based on the solution of improved Boussinesq. Then according to soil movement and stress transfer approach，the rational passive load distribution of isolation piles is obtained by improving local deformation theory of plasticity considering soil arching. Finally，differential equations of elastic and plastic regions of isolated piles are established by considering the gravity second-order effect caused by lateral load and yield of soil for tri-parameter Winkler elastic foundation beam model. Combining matrix transfer method with Laplace forward and inverse transformation，the numerical solution of passive mechanical features of isolation piles is obtained. Later，the proposed approach is verified by the test data. The results indicate that the numerical and measured results are in good agreement，and the proposed approach is applicable in engineering practice.