考虑桩-土相互作用的悬臂式排桩内力计算方法研究

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

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.

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 nonlin-ear function relationship between earth pressure and pile displacement in or out of the foundation pit was assumed,and then the nonlinear function array of j oint loads was established.Thirdly,the overall stiffness equation was formed ac-cording 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 calcu-lated with the elemental stiffness equations and nodal displacement array.The example analysis shows that the pro-posed method is simple and convenient,fully reflecting the characteristics of nonlinear variation of earth pressure act-ing on piles,and revealing the mechanism of pile-soil interaction well.Therefore,it is suitable for the internal force calculation of cantilever piles.