The mining industry is frequently subjected to various disasters,one of the major concerns is water-related disasters,particularly seam floor water inrush.These disasters pose significant threats to the safety and pro...The mining industry is frequently subjected to various disasters,one of the major concerns is water-related disasters,particularly seam floor water inrush.These disasters pose significant threats to the safety and production of deep coal mines.The primary reason for this is that the fracturing of the rock mass induces the formation of a fluid(water)with both kinetic and potential energy.In this paper,a novel water inrush mechanism for deep floor failure due to water hammer effects is proposed based on the Xingdong coal mine in China.The water hammer pressure within rock pore channels has a different impact on the surrounding rock,leading to the degradation of the rock mass channel through repeated conduction and instantaneous cutoff.To further investigate this phenomenon,a progressive corrosion fracture mechanics(PCFM)model induced by a water hammer is established.The results show that the water hammer pressure caused by instantaneous channel truncation increases with increasing water flow velocity.The chemical damage factor(i.e.,stress corrosion fracture)is also incorporated into the Dugdale-Barenblatt(D-B)model to analyze the factors influencing the PCFM.These findings indicate that the greater the degree of damage is,the more likely the concealed fault is to experience water inrush.Finally,methods for controlling water inrush caused by the water hammer effects of deep floors are proposed.The failure mechanisms of the water hammer and the PCFM provide theoretical and practical guidance for controlling water inrush from the deep floor.展开更多
This study investigates the fracture characteristics and the fracture process zone(FPZ)of mode I fracture in sandstone,aiming to analyze the propagation behaviors of mode I crack under different freeze-thaw cycles.Sem...This study investigates the fracture characteristics and the fracture process zone(FPZ)of mode I fracture in sandstone,aiming to analyze the propagation behaviors of mode I crack under different freeze-thaw cycles.Semicircular bending tests(SCB)were conducted using different freeze-thaw cycles to evaluate mode I fracture toughness,FPZ dynamics,and macroscopic microscopic features.Digital image correlation(DIC)and scanning electron microscopy(SEM)techniques were employed for detailed analysis.Experimental results reveal that freeze-thaw cycling leads to the widening of both preexisting and newly formed microcracks between internal particles.Under external loading,crack propagation deviates from prefabricated paths,forming serrated crack patterns.The FPZ initiates at the prefabricated crack tip and extends toward the loading end,exhibiting an arcshaped tip shape.The FPZ length increases with loading but decreases after reaching a peak value.With additional freeze-thaw cycles,the maximum FPZ length first increases and then diminishes.展开更多
For coal mines,rock,coal,and rock bolt are the critical constituent materials for surrounding rock in the underground engineering.The stability of the“rock-coal-bolt”(RCB)composite system is affected by the structur...For coal mines,rock,coal,and rock bolt are the critical constituent materials for surrounding rock in the underground engineering.The stability of the“rock-coal-bolt”(RCB)composite system is affected by the structure and fracture of the coal-rock mass.More rock bolts installed on the rock,more complex condition of the engineering stress environment will be(tensile-shear composite stress is principal).In this paper,experimental analysis and theoretical verification were performed on the RCB composite system with different angles.The results revealed that the failure of the rock-coal(RC)composite specimen was caused by tensile and shear cracks.After anchoring,the reinforcement body formed inside the composite system limits the area where the crack could occur in the specimen.Specifically,shearing damage occurred only around the bolt,and the stress-strain curve presented a better post-peak mechanical property.The mechanical mechanism of the bolt under the combined action of tension and shear stress was analyzed.Additionally,a rock-coal-bolt tensile-shear mechanical(RCBTSM)model was established.The relationship(similar to the exponential function)between the bolt tensile-shear stress and the angle was obtained.Moreover,the influences of the dilatancy angle and bolt diameter of the RCB composite system were also considered and analyzed.Most of the bolts are subjected to the tensile-shearing action in the post-peak stage.The implications of these results for engineering practice indicated that the bolts of the RCB composite system should be prevented from entering the limit shearing state early.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.52225404 and 52404121)the Key Research and Development Program Projects of Xinjiang Uygur Autonomous Region(Grant No.2024B03017).
文摘The mining industry is frequently subjected to various disasters,one of the major concerns is water-related disasters,particularly seam floor water inrush.These disasters pose significant threats to the safety and production of deep coal mines.The primary reason for this is that the fracturing of the rock mass induces the formation of a fluid(water)with both kinetic and potential energy.In this paper,a novel water inrush mechanism for deep floor failure due to water hammer effects is proposed based on the Xingdong coal mine in China.The water hammer pressure within rock pore channels has a different impact on the surrounding rock,leading to the degradation of the rock mass channel through repeated conduction and instantaneous cutoff.To further investigate this phenomenon,a progressive corrosion fracture mechanics(PCFM)model induced by a water hammer is established.The results show that the water hammer pressure caused by instantaneous channel truncation increases with increasing water flow velocity.The chemical damage factor(i.e.,stress corrosion fracture)is also incorporated into the Dugdale-Barenblatt(D-B)model to analyze the factors influencing the PCFM.These findings indicate that the greater the degree of damage is,the more likely the concealed fault is to experience water inrush.Finally,methods for controlling water inrush caused by the water hammer effects of deep floors are proposed.The failure mechanisms of the water hammer and the PCFM provide theoretical and practical guidance for controlling water inrush from the deep floor.
基金supported by the projects(Grant No.:52304118)supported by National Natural Science Foundation of China,the Scientific Research Foundation for High-level Talents of Anhui University of Science and Technology(2023yjrc18)the Open Fund of the State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mine(Grant No.:SKLMRDPC23KF08).
文摘This study investigates the fracture characteristics and the fracture process zone(FPZ)of mode I fracture in sandstone,aiming to analyze the propagation behaviors of mode I crack under different freeze-thaw cycles.Semicircular bending tests(SCB)were conducted using different freeze-thaw cycles to evaluate mode I fracture toughness,FPZ dynamics,and macroscopic microscopic features.Digital image correlation(DIC)and scanning electron microscopy(SEM)techniques were employed for detailed analysis.Experimental results reveal that freeze-thaw cycling leads to the widening of both preexisting and newly formed microcracks between internal particles.Under external loading,crack propagation deviates from prefabricated paths,forming serrated crack patterns.The FPZ initiates at the prefabricated crack tip and extends toward the loading end,exhibiting an arcshaped tip shape.The FPZ length increases with loading but decreases after reaching a peak value.With additional freeze-thaw cycles,the maximum FPZ length first increases and then diminishes.
基金Beijing Outstanding Young Scientist Program(BJJWZYJH01201911413037)the projects supported by National Natural Science Foundation of China(Grants Nos.41877257,51622404,and 51974117)Shaanxi Coal Group Key Project(2018SMHKJ-A-J-03)。
文摘For coal mines,rock,coal,and rock bolt are the critical constituent materials for surrounding rock in the underground engineering.The stability of the“rock-coal-bolt”(RCB)composite system is affected by the structure and fracture of the coal-rock mass.More rock bolts installed on the rock,more complex condition of the engineering stress environment will be(tensile-shear composite stress is principal).In this paper,experimental analysis and theoretical verification were performed on the RCB composite system with different angles.The results revealed that the failure of the rock-coal(RC)composite specimen was caused by tensile and shear cracks.After anchoring,the reinforcement body formed inside the composite system limits the area where the crack could occur in the specimen.Specifically,shearing damage occurred only around the bolt,and the stress-strain curve presented a better post-peak mechanical property.The mechanical mechanism of the bolt under the combined action of tension and shear stress was analyzed.Additionally,a rock-coal-bolt tensile-shear mechanical(RCBTSM)model was established.The relationship(similar to the exponential function)between the bolt tensile-shear stress and the angle was obtained.Moreover,the influences of the dilatancy angle and bolt diameter of the RCB composite system were also considered and analyzed.Most of the bolts are subjected to the tensile-shearing action in the post-peak stage.The implications of these results for engineering practice indicated that the bolts of the RCB composite system should be prevented from entering the limit shearing state early.
