堆载作用下考虑土拱效应的被动桩变形内力半解析解

Semi-analytical solution to deformation and internal force of passive piles under surcharge loads considering soil arching effect

为分析桩侧堆载作用下被动桩受力特性,首先在布辛奈斯克(Boussinesq)改进解的基础上推导出堆载作用下地基土体的水平附加应力计算公式,进而得到被动桩基被动侧土压力计算表达式。在此基础之上,从土体的运动和应力传递方式入手,对考虑被动侧成拱的Ito局部塑性变形理论进行改进,从而解得被动桩桩身被动荷载分布。最后,根据考虑轴向荷载P效应影响的三参数非线性弹性地基梁模型建立被动桩桩身弹性段与塑性段的微分方程组,求解过程中应用矩阵传递法结合Laplace正逆变换解得被动桩变形与内力的半解析解,并用试验数据对半解析解进行验证。结果表明,理论解与试验数据吻合较好。

In order to analyze the behaviors of the passive piles under surcharge loads, firstly, a formula for the additional horizontal stress of subsoil is deduced from the modified solutions of Boussinesq. Furthermore, the computational expressions for the soil pressure on the passive side of passive piles are gained. Then, based on the soil movement and stress transfer approach, the distribution of passive load of passive piles is drawn by means of the improved theory of partial plastic deformation. Finally, differential equations for the elastic and plastic section of passive piles are established by using the tri-parameter nonlinear elastic foundation beam model considering the P-A effect which is caused by lateral load. The original method of combining Matrix-transfer-method with Laplace forward transformation and Laplace inverse transformation is used to solve the deformation and internal force of passive piles influenced by the surcharge loads. The proposed approach is verified by the data from an experiment. The results indicate that the computed and test results are in good agreement. The proposed approach has reference value for studying the bearing mechanism of passive piles due to surcharge loads.