剪切型Beam Lattice模型及其在岩石翼裂纹扩展和贯通模拟中的应用

Shear-enhanced Beam Lattice model and its application in simulation of propagation and coalescence of wing crack in geomaterials

采用考虑剪切效应和Mohr-Coulomb失效准则的剪切型Beam Lattice(SBL)模型来模拟翼裂纹扩展和贯通过程中出现的次生裂纹.该模型采用随机多边形网格来反映材料的非均质性,在结果分析中应用裂纹扩展路径来区分张拉型和剪切型裂纹扩展.利用SBL模型对不同间距的初始裂纹进行模拟,并将模拟结果和实验观测结果进行比对.结果表明,SBL模型可以较为准确地模拟不同模式下的裂纹扩展和贯通路径.翼裂纹的扩展和贯通呈现阶段性,首先出现张拉型裂纹,当裂纹间距为10 mm时出现清晰的贯通裂纹,最后出现剪切型裂纹.裂纹的扩展进程在加载前中期保持稳定,而在加载末期时明显加快,出现不稳定扩展的现象.SBL模型中考虑更多的剪切效应会得到更多的剪切型裂纹.

A shear-enhanced Beam Lattice（ SBL） model considering the shear effect and the MohrCoulomb failure criterion is applied to simulate the secondary cracks and wing cracks during propagation and coalescence. In this model,the random polygonal mesh is used to reflect the heterogeneity of materials. In the result analysis,the crack propagation path is applied to distinguish the shear type and the tensile type of crack propagation. The SBL model is applied to simulate the fracture of the flaws with different spacing,and the simulation results are compared with the experimental ones.The results showthat the propagation and the coalescence of the flaws under different modes can be well simulated by using the SBL model. The propagation and the coalescence process exhibit several stages. The tensile cracks appear first,and then the obvious coalescence cracks occur when the flawspacing is 10 mm. The shear cracks appear at the final stage. During the initial and middle loading stages,the propagation process is stable. However,it accelerates and becomes unstable in the final stage. More shear effects in the SBL model can result in more shear cracks.