基于有限差分与离散元耦合的支挡结构数值计算方法

Numerical method for retaining structures based on coupled finite difference method and discrete element method

土体与支挡结构的变形与稳定是岩土工程界关注的一个重要问题。作为探讨,介绍了运用快速拉格朗日有限差分与颗粒离散单元外部耦合的方法,对处于系统中的不同部位,分别应用二维刚性颗粒离散单元与允许大应变的有限差分网格,模拟离散体与结构物的相互作用,连续域与非连续域的平滑过渡则通过计算过程中满足两域对应边界的相容条件与平衡条件实现。就耦合的实现途径进行了说明,并将其应用于衡重式挡墙与墙后填土相互作用的分析,对比计算结果与现场实测数据,证明采用的方法能较有效地再现土与支挡结构的力学变形规律。

Deformation and stability due to the interaction between soil and retaining structures are the primary problems in geotechnical engineering. As a part of the continuous effort, the authors introduce an approach to simulate the soil-structure interaction numerically using the combined FLAC （Fast Lagrangian Analysis of Continua） and DEM, in which the soil is simplified as the collection of packing particles of rigid disks to be described by DEM while the retaining structure is viewed as one with the possibility of large strain and can be analyzed by the finite difference method. Smooth transition across the continuous/discontinuous domains is obtained by imposing the compatibility condition and equilibrium condition along the boundaries in the course of computation. Application of the proposed approach is discussed. A case study of a shoulder retaining wall acted by soil backfills is provided thereafter, showing the applicability of the proposed method.