基于加荷和卸荷模型的分区破裂化初步模拟及空间局部化机理

为了采用数值模拟方法模拟出深部巷道围岩的分区破裂或碎裂化现象,采用了两种三维力学模型,即加荷模型和卸荷模型,在计算中考虑了岩石材料的应变软化非均质性质.在加荷模型中,巷道被一次性开挖之后再进行位移控制加载.在卸荷模型中,当模型已处于静力平衡状态之后,巷道被分步开挖.计算结果表明:在上述两种条件下,在垂直于巷道轴线的平面内,都出现了剪切应变增量的高、低值区相间隔的现象.此外,卸荷模型的结果要比加荷模型的结果更符合实际.分区破裂化现象被认为是由若干呈锥面分布的空间剪切带形成的.

Preliminary numerical simulation of zonal disintegration phenomenon based on loading and unloading models and the mechanism of spatial strain localization

In order to simulate the zonal disintegration phenomenon of rock mass around deep tunnel,this study proposes two types of three-dimensional strain-softening heterogeneous mechanical models,i.e.,loading model and unloading model.In the loading model,after a cylindrical tunnel is excavated at one time,the displacement-controlled loading is applied in the direction perpendicular to the tunnel axis.However,in the unloading model,after the model has reached a static equilibrium state,a cylindrical tunnel is excavated step by step.Numerical results show that under these two conditions,the phenomenon of isolated annular regions with higher or lower shear strain increments is observed in planes orthogonal to the tunnel axis.In addition,the results based on the unloading model are closer to the actual situations than that based on the loading model.The zonal disintegration phenomenon is believed to be formed by several spatial cone-shape shear bands.