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| Particle flow simulation of rock burst and roof fall of deep coal roadway under dynamic disturbance |
| JING Hongwen，WU Jiangyu，YIN Qian，SHI Xinshuai，ZHAO Zhenlong |
| (State Key Laboratory for Geomechanics and Deep Underground Engineering，China University of Mining and Technology，Xuzhou，Jiangsu 221116，China) |
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Abstract In order to study the mechanism of disaster caused by rock burst and roof fall of rectangular coal roadway in kilometer deep，this paper based on the engineering background of roadway with rock burst and roof fall of Longyun coal industry in Shandong，the two media-four boundaries model of the surrounding rock structure supported by the rockbolt and anchor cable was proposed by particle flow software PFC2D，the microscopic structure evolution characteristic of the roadway during the complete rock burst and roof fall under the coupling impacts of high stress and dynamic disturbance was simulated. The effects of the rock burst on the displacement field，force chain field，crack field，failure mode，roof kinetic energy evolution and roof contact stress of roadway surrounding rock under different support schemes were analyzed. The anchorage and failure mechanisms of the rockbolt and anchor cable were revealed from the microscopic level. The results show that the coupling impacts of high stress and dynamic disturbance on the coal roadway in deep cause the high elastic energy accumulated in the rock mass to release instantaneously. It results in the fractures of the force chains among rock mass，rockbolt and anchor cable，which presents the distribution characteristics of intermittent force chains. The deteriorations of intermittent force chains and concentrated chain area cause the anchoring failure of rockbolt and anchor cable，thereby resulting in the rock burst and roof fall. The tensile and shear cracks are prone to occur at the anchoring interfaces of the rockbolt and anchor cable，and it shows sudden accumulation，which causes the propagation and coalescence of tensile and shear cracks developed at the top of the anchor cable to form the obvious fissure delamination. The anchor cable crossing the interface between coal seam and direct roof is more prone to fracture under the effects of interface shear stress and tensile stress of the rockbolt-coal rock composite，and it is usually accompanied by the accumulation of tensile and shear cracks there. The support action of the rockbolt is to form a rockbolt-coal rock composite structure had complete force chains with the coal and rock，which ensures the integrity and loading capacity of the surrounding rock and inhibits the development of tensile and shear cracks in the anchoring area. The support action of the anchor cable is to form a concentration area of stable force chains with the hard rock at the top，suspend the rock mass in the anchoring area to the top hard rock strata，and prevent the roof fall of top rock mass. Based on the above analysis，the supporting principle was proposed to strengthen the integrity and loading capacity of the surrounding rock and optimize the fracture limit of the anchor cable，which provides a new point for preventing and controlling the rock burst and roof fall of deep coal roadway.
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2020, Vol. 39 
