Meitan xuebao (May 2023)
Evolution and mechanism of rockburst induced by structural plane based on GDEM
Abstract
In the process of deep underground rock excavation, the surrounding rock of cave wall often causes some rockburst geological disasters due to the weakening of structural plane. In order to reveal the influence of the existence of structural plane on the rockburst induction mechanism, in this paper, adopting the finite element and discrete element coupled GDEM numerical simulation technology, the influences of the number and scale of vertical structural planes on the mechanical characteristics of rock cracking propagation, stress, displacement and slab velocity of deep hard rock straight arch tunnel under excavation and unloading are studied, and the evolutionary mechanism between wall cracking and structural plane rockburst is revealed. Results indicate that the failure modes and intensity for the surrounding rock with multiple structural planes are associated with the controlling effect of the structural plane, especially within 1.5 m away from the tunnel side, and the weak plane can act as the boundary of the rockburst cater. The uneven distribution of the tangential stress and the eccentric compression of the rock plates separated by the weak plane will induce intense slabbing rockburst. The size of the structural plane will also affect the intensity of the surrounding rock failure, and the stress transfer to the deep rockmass will be impeded. Three-jointed rock slab with large scale and high flexibility has high end load strength and obvious buckling effect of rock slab, which leads to radial internal rock slab buckling and triggering shear instability failure at the end of side wall surrounding rock slab and strong rock burst. However, with the small and medium scale three-jointed slab, the flexibility of the rock plate is small and the rock plate is stable, leading to the quasi-static brittle failure of the surrounding rock, and forming a small V-type destructive fracture port.
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