The surface subsidence or slope slip disasters are easily induced by the collapsing pillar in the room and pillar goaf.In this study,typical instability cases in southwest mining area of China were investigated.The physical and numerical modeling were then carried out.The moving law of overburden rock,the deformation and failure mechanism of slope induced by the gradual weakening and collapse of pillar are studied.The results show that after the mining of the room,the stress of the rock mass was redistributed,stress concentration could be caused at the boundary of the goaf and the pillar.The local collapse of roof occurred at the position below the slope toe.When the pillar was weakening and fails to bear the weight of the overlying rock mass,the roof would start to bend and sink.Under the action of gravity.the cracks expanded from the boundary of the goaf to the overlying rock mass,forming the"collapse arch".When the vertical crack was induced in the slope,the rock mass on the right side of the crack moved outside the slope.The rock mass at the foot of the slope was gradually broken due to the compression of the overlying rock mass and the shear deformation of the roof.The broken rock mass in the middle and lower part of the slope was squeezed outward,which induces the collapse of the slope.Generally,the process of slope collapse induced by the gradual instability of the pillar can be divided into four stages as follow:the collapse stage of the roof rock mass in the goaf,the formation of the penetrating crack stage,the toppling instability stage of the slope and the buckling collapse.
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