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Abstract
Aiming at the large deformation instability problem caused by the excavation unloading of a coal roadway in deep-buried slowly inclined jointed rock mass, the geomechanical parameters and deformation failure characteristics of an engineering geomechanical model were investigated. The in-situ stress state of the model was measured with the stress relief method. The geological and mechanical properties of roadway surrounding rock were described. The surrounding rock structure was revealed with the electron microscopy scanning method, micro-fractures and randomly distributed joints highly developed in roadway surrounding rock. Field investigation and monitoring indicated the cross-section of roadway surrounding rock shrank continuously and the deformation distribution was obviously asymmetric. Shotcrete spalling and cable broken failures frequently occurred in the middle and ride side of roof and right rib. Based on the geomechanical conditions of the coal roadway, a discrete element numerical model of coal roadway in gently inclined jointed rock mass was established. The parameters of rock mass in the numerical model were calibrated. The model ran in unsupported condition to restore the evolution process of stress, crack propagation and deformation in roadway surrounding rock due to gradual deviatoric stress release caused by excavation. On this basis, the space-time evolution characteristics and law of stress, crack propagation and deformation were obtained and then the asymmetric large fragmentation and dilatation deformation failure mechanism of roadway surrounding rock in deep-buried slowly inclined jointed rock mass was revealed. The failure reasons of the support structure were analyzed, and the relevant support principles were proposed. The research results can provide scientific references for the stability control of roadways excavated in jointed rock mass.
Highlights
Coal is the fundamental resources of the global economy, accounting for 30% of the world’s total energy consumption [1]
In view of the above scientific problems in roadway drivage, the coal roadway in gently inclined jointed rock mass was taken as the engineering background in this study, using the discrete element numerical model to reproduce the process of crack initiation, incorporation and large deformation failure due to the gradual release of deviatoric stress in surrounding rock
The asymmetric large deformation law, stress distribution characteristics and failure mechanism of jointed surrounding rock mass due to excavation unloading were revealed. These results provide a reliable scientific basis for the rational stability control of coal roadway in deep gently inclined jointed rock mass and effectively guarantee the safe and efficient mining of coal mines in China
Summary
Coal is the fundamental resources of the global economy, accounting for 30% of the world’s total energy consumption [1]. In view of the above scientific problems in roadway drivage, the coal roadway in gently inclined jointed rock mass was taken as the engineering background in this study, using the discrete element numerical model to reproduce the process of crack initiation, incorporation and large deformation failure due to the gradual release of deviatoric stress in surrounding rock. The asymmetric large deformation law, stress distribution characteristics and failure mechanism of jointed surrounding rock mass due to excavation unloading were revealed
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