圆形巷道围岩层裂或板裂化的等效连续介质模型及侧压系数的影响

为了避免均质和非均质模型不能较好地模拟围岩的层裂或板裂化现象，将岩石视为等效连续介质，即颗粒体材料。颗粒被视为弹性材料，而颗粒之间的界面破坏后被视为摩尔-库仑材料。颗粒和界面均被离散为正方形单元。采用FLAC研究了不同侧压系数时圆形巷道围岩中的剪切应变增量、最小、最大主应力等的分布规律。研究发现，颗粒体材料模型在压应力作用下诱发出的拉应力值接近于在模型边界上所施加的最大压应力，而最大压应力是所施加的最大压应力的数倍。这些结果意味着均质和非均质模型的计算结果是偏于不安全的。另外，最小主应力和剪切应变增量的等值线图均显示，这些量的高值区的距离大致相等，这与V形岩爆坑内的板裂化现象类似。围岩层裂现象的原因是环向的高压应力和径向的高拉应力的共同作用的结果。

An equivalent continuum model for exfoliation or slabbing phenomenon of surrounding rock of circular tunnel and effects of lateral pressure coefficients

To overcome the shortcoming of the homogeneous and heterogeneous models that cannot successfully model the exfoliation or slabbing phenomenon of the surrounding rock,the rock is treated as an equivalent continuum,i.e.the granular assembly.The granular and interfaces are divided into square elements.The distribution of the shear strain increment,minimum principal stress and maximum principal stress in the surrounding rock of circular tunnel model at different lateral pressure coefficients are studied.It is found that the maximum induced tensile stresses within the model under compressive stress are closer to the applied maximum compressive stresses,while the maximum compressive stresses within the model are greatly higher than the applied maximum compressive stresses.Numerical results using FLAC suggest that the homogeneous and heterogeneous models give unsafe results.The contour maps of the shear strain increment and the minor principal stress show equidistant characteristics of their highest values zones,which is similar to the observed exfoliation phenomenon in the formation process of a V-shaped rockburst notch.Numerical results show that the reason for the exfoliation or slabbing of the surrounding rock is due to the high loop compressive stress and radial tensile stress.