考虑桩-土相互作用的悬臂式排桩内力计算方法研究

在分析常用计算方法优缺点的基础上,通过引入非线性的桩-土相互作用模型,提出了一种可考虑桩-土相互作用的悬臂式排桩内力计算方法.首先,采用杆单元对桩体结构进行离散化,计算单元刚度矩阵并合成为总体刚度矩阵;其次,假定基坑内、外侧土压力与桩身位移之间的非线性函数关系,建立非线性的节点荷载函数列阵;再次,根据总体刚度矩阵和节点荷载函数列阵形成总体刚度方程(组),采用Newton-Raphson法求解以得到节点位移列阵;最后,通过单元刚度方程和节点位移列阵反求桩身内力和桩侧土压力.算例分析表明,本文方法计算简单方便,能充分反映桩侧土压力非线性变化的特点,较好地揭示了桩-土相互作用机理,适用于悬臂式排桩内力计算.

Research on the Internal Forces Calculation of Cantilever Piles Considering Pile-soil Interaction

By analyzing the advantages and disadvantages of commonly used calculation methods and introducing a nonlinear pile-soil interaction model, a method for calculating the internal forces of cantilever piles was proposed, which can consider the pile-soil interaction. Firstly, finite bar elements were used to discretize the pile structures, and then, elemental stiffness matrixes were calculated and incorporated into global stiffness matrix. Secondly, the nonlinear function relationship between earth pressure and pile displacement in or out of the foundation pit was assumed, and then the nonlinear function array of joint loads was established. Thirdly, the overall stiffness equation was formed according to the global stiffness matrix and nodal load function array, and was solved to obtain the nodal displacement array by using the Newton-Raphson method. Finally, the internal forces of pile and lateral earth pressure were calculated with the elemental stiffness equations and nodal displacement array. The example analysis shows that the proposed method is simple and convenient, fully reflecting the characteristics of nonlinear variation of earth pressure acting on piles, and revealing the mechanism of pile-soil interaction well. Therefore, it is suitable for the internal force calculation of cantilever piles.