铁路路基桩板结构荷载扩散模式及有限元计算方法研究

Research on Load Diffusion Mode and Finite Element Method of Pile-slab Structure of Railway Subgrade

桩板结构由于具有优越的刚性特征,在软土、岩溶、采空区、短路基、交叉工程等条件复杂地区加固地基取得了良好效果,但因其荷载复杂、结构多次超静定,往往需借助国外商业有限元计算软件进行结构设计优化。采用理论研究与数值计算方法,对路基桩板结构计算模型、荷载扩散模式、有限元计算方法进行研究。研究表明:桩板结构可借助温克尔弹性地基梁理论简化为二维梁-杆框架结构;路基基床结构与桩板结构组成的“上软下硬”双层地基结构体系下,路基各类荷载扩散至桩板结构上的扩散角范围为0°~30°;通过构建有限元理论框架下梁、杆单元刚度矩阵与温度等效荷载,自主编制了桩板结构V1.0结构计算软件,对比商业有限元软件与自编软件的内力与位移计算结果,显示两者高度吻合,可服务于工程设计。

The pile-slab structure has been widely used in foundation reinforcement projects with complex engineering conditions, such as subgrades with soft soil, karst treatment, mined-out areas, short subgrades, and crossing projects because of its excellent rigidity. However, due to the complex loads and statically indeterminacy, structure calculations of the pile-slab structure are often conducted by means of foreign commercial FEM computation software. This paper studies the calculation model of pile-slab structure, load transfer mode and structure calculation method in the frame of finite element method. The conclusions are as follows:(1) with the help of Winkler’s elastic foundation beam theory, the pile-slab structure could be simplified to a two-dimensional beam-bar frame structure, which can be easily dispersed with FEM;(2) with the load transfer mode from the subgrade bed structure to the pile-slab structure, which forms a “soft top and hard bottom” double-layer foundation system, the diffusion angle of different subgrade loads to pile-slab structure is ranged from 0°to 30°;(3) rigidity matrices of the beam and rod elements in the frame of FEM theory, as well as the temperature load equivalent method, are constructed, and a software named Pile-Slab Structure V1.0 is independently compiled, Internal forces and displacements calculated by commercial FEM software and self-compiled software are compared, showing that the calculation results are highly consistent and the software could be used for engineering design.