Dynamic and static load effect of non-uniformly"bow-shaped"super-thick key strata
The rupture of super-thick key strata is a crucial factor in triggering mine dynamic disasters.Investigating the impact of their non-uniform thickness on mining-induced stress environments and rupture dynamic loads,and further re-vealing the mechanism of dynamic and static loading on rock burst pressure,is the theoretical foundation for predicting rock burst risks and disaster prevention and control.This paper investigates the non-uniformly thick"bow-shaped"super-thick key strata in the Binchang mining area of Shaanxi.Through comprehensive theoretical analysis and numerical simu-lation,it analyzes the mechanical principle of abnormal stress concentration in the coal rock mass beneath the"bow-shaped"super-thick key strata,clarifies the influence of the"bow-shaped"morphology on the rupture characteristics of the super-thick key strata and reveals the mechanism of dynamic and static load superposition in the area beneath the"bow-shaped"formation,leading to rock bursts.Based on the study above,a method for predicting the disaster risks caused by the rupture of"bow-shaped"super-thick key strata is proposed.The results show that in the convex area under the"bow-shaped"formation of the super-thick key strata,the high stress is exceptionally concentrated,increasing the coal rock body stress by an additional 22.1 MPa,with an increase rate of up to 56%,which is the fundamental reason for the high static load formation in the underlying coal-rock body.At the same time,the principal stress in the concave area of the"bow-shaped"formation concentrates and undergoes significant deformation,increasing the risk of strong dynamic loads due to rupture.Under the combined action of dynamic and static loads in the non-uniformly thick"bow-shaped"super-thick key strata,the rock bursts are likely to occur in the pillar and roadway areas.The proposed method for predicting the disaster risks due to the rupture of"bow-shaped"super-thick key strata effectively guides the disaster prevention and control in high-risk mining areas prone to rock bursts.Additionally,the distributed fiber optic field measurement results validate the intrinsic connection between the rupture of super-thick key strata and the generation of dynamic loads.
Non-uniform rock stratasuper-thick key strataabutment stressrockburstroof disasterdeep mining
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