The stability and fracture behavior of a goaf roof beneath an open-pit bench are critical concerns,especially under impact loading.However,the effect of the thickness-to-span ratio on dynamic failure modes remains lar...The stability and fracture behavior of a goaf roof beneath an open-pit bench are critical concerns,especially under impact loading.However,the effect of the thickness-to-span ratio on dynamic failure modes remains largely unexplored,as existing research focuses mainly on static stability.Energy dissipation and instability evolution under impact loading require further study.To address this gap,this study conducts drop-weight impact experiments on specimens with circular perforations,complemented by numerical simulations.By integrating dimensional analysis,cusp catastrophe theory,and strength reduction techniques,the dynamic instability mechanism of goaf roofs with varying thickness-to-span ratios is revealed.Results show that the thickness-to-span ratio significantly influences energy accumulation and dissipation during roof failure.A higher ratio increases both the magnitude and rate of energy dissipation,particularly during crack initiation and stable propagation,while its impact diminishes in the final failure stage.Optimizing the thickness-to-span ratio within a critical range enhances structural stability,improving the safety factor by up to 83%.However,beyond a certain threshold,additional thickness yields diminishing benefits.This study provides new insights into the energy-based instability mechanism of goaf roofs under impact loads,establishing a theoretical foundation for early warning systems and optimized safety design.展开更多
Cross roadway collapses are a common occurrence in underground mining operations.While the influence of mining blasts on the stability of surrounding rock is acknowledged,the underlying mechanisms remain inadequately ...Cross roadway collapses are a common occurrence in underground mining operations.While the influence of mining blasts on the stability of surrounding rock is acknowledged,the underlying mechanisms remain inadequately understood.This study investigates the characteristics and mechanisms of collapse in a shallow buried cross roadway subjected to mining blast disturbances,drawing insights from an engineering project in Anshan City,Northeast China.A strain-softening model based on unified strength theory was developed to effectively calculate and analyze the loosened zone thickness and surrounding rock displacement.The PFC3D-FLAC3D coupling method was employed to clarify the concentrated collapse area within the cross roadway,providing insight into the collapse mechanism through a cross-sectional model of the concentrated region.Results demonstrate that 50%of the cross roadway collapsed following the mining blast.Subsidence at the intersection was approximately one-fifth(0.66 m)of cross roadway’s net height,exceeding subsidence in other areas by 1.3.Under the action of repeated mining blasting,the cross section of the connection roadway forms a semi-elliptical high tensile stress zone.After the cumulative damage of the surrounding rock of the connection roadway exceeds the ultimate yield strength,the cumulative stress release causes the tensile failure of the surrounding rock.The plastic zone of the connecting roadway expands to three times of the initial,and continues to develop.The surrounding rock on both sides experienced tensile stress,cumulative stress release,and the vertical propagation of tensile cracks.展开更多
基金support from the Natural Science Foundation of Jiangsu Province(Grant No.BK20242059)the Collaborative Innovation Center for Prevention and Control of Mountain Geological Hazards of Zhejiang Province(PCMGH-2023-02)the opening fund of State Key Laboratory of Coal Mine Disaster Dynamics and Control(2011DA105827-FW202209)are gratefully acknowledged.
文摘The stability and fracture behavior of a goaf roof beneath an open-pit bench are critical concerns,especially under impact loading.However,the effect of the thickness-to-span ratio on dynamic failure modes remains largely unexplored,as existing research focuses mainly on static stability.Energy dissipation and instability evolution under impact loading require further study.To address this gap,this study conducts drop-weight impact experiments on specimens with circular perforations,complemented by numerical simulations.By integrating dimensional analysis,cusp catastrophe theory,and strength reduction techniques,the dynamic instability mechanism of goaf roofs with varying thickness-to-span ratios is revealed.Results show that the thickness-to-span ratio significantly influences energy accumulation and dissipation during roof failure.A higher ratio increases both the magnitude and rate of energy dissipation,particularly during crack initiation and stable propagation,while its impact diminishes in the final failure stage.Optimizing the thickness-to-span ratio within a critical range enhances structural stability,improving the safety factor by up to 83%.However,beyond a certain threshold,additional thickness yields diminishing benefits.This study provides new insights into the energy-based instability mechanism of goaf roofs under impact loads,establishing a theoretical foundation for early warning systems and optimized safety design.
基金This research was supported by the National Natural Science Foundation of China(Grant Nos.51974187)Intelligent Mine Blasting and Innovative Technology Platform Construction(LJ232410146045)Liaoning Revitalization Talents Program(XLYC2203173).
文摘Cross roadway collapses are a common occurrence in underground mining operations.While the influence of mining blasts on the stability of surrounding rock is acknowledged,the underlying mechanisms remain inadequately understood.This study investigates the characteristics and mechanisms of collapse in a shallow buried cross roadway subjected to mining blast disturbances,drawing insights from an engineering project in Anshan City,Northeast China.A strain-softening model based on unified strength theory was developed to effectively calculate and analyze the loosened zone thickness and surrounding rock displacement.The PFC3D-FLAC3D coupling method was employed to clarify the concentrated collapse area within the cross roadway,providing insight into the collapse mechanism through a cross-sectional model of the concentrated region.Results demonstrate that 50%of the cross roadway collapsed following the mining blast.Subsidence at the intersection was approximately one-fifth(0.66 m)of cross roadway’s net height,exceeding subsidence in other areas by 1.3.Under the action of repeated mining blasting,the cross section of the connection roadway forms a semi-elliptical high tensile stress zone.After the cumulative damage of the surrounding rock of the connection roadway exceeds the ultimate yield strength,the cumulative stress release causes the tensile failure of the surrounding rock.The plastic zone of the connecting roadway expands to three times of the initial,and continues to develop.The surrounding rock on both sides experienced tensile stress,cumulative stress release,and the vertical propagation of tensile cracks.
