土坝裂缝开展的无单元法数值模拟

结合压实黏土拉伸状态下的脆性断裂模型和弥散裂缝理论,提出了点插值无单元法模拟土石坝坝体裂缝开展过程的数值计算方法。当压实黏土达到其抗拉强度后,在每个积分点建立各向异性刚度矩阵,并构造了平面应变条件下考虑压实黏土脆性开裂的无单元与有限元耦合的计算模式。开发的结点自动加密技术对坝体的拉应力区域进行自动结点加密,并根据可视准则确定无单元结点的影响域。以最小结点间距为开裂步长,通过对坝体裂缝离心模型试验的模拟计算,检验了脆性断裂模型和无单元算法对土体拉伸裂缝发展过程的适用性。

Meshless method for numerical simulation of crack propagation in earth dams

Based on the brittle fracture model of compacted cohesive soil in tensile stress and the smeared cracking theory,a point interpolation meshless method is proposed for a 2D simulation of crack propagation in earth dams.For a plane strain problem,the anisotropic stiffness matrix at each integration point is constructed for post-tensile failure zones.Then a meshless method is proposed for the brittle fracture in compacted cohesive soil.The nodes in the tensile stress zone are automatically refined and the influence domain of a node is defined according to the visibility criterion of a crack barrier.The minimal space between nodes is used as cracking step.This meshless method is applied to the simulation of three centrifuge model tests on crack propagation in an earth dam.The simulation results show that the combination of brittle fracture model and meshless algorithms is able to capture the initiation and propagation of cracks induced by tensile failure.