关键词: 等效连续介质, 圆形巷道, 层裂, 等间距, 拉应力, 板裂化, 岩爆

Abstract: 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.

Key words: equivalent continuum, circular tunnel, exfoliation, same spacing, tensile stress, slabbing, rockburst