The Surrounding Rock Stress And Overlying Strata Movement Law In Dongjiahe Coal Mine

Coal mining is easy to cause accident under complex geological conditions and it is a constraint of Chinese coal industry safe and efficient development.Among them,the face of mining roof accidents most often occur.Therefore,it is urgent to study the law of surrounding rock stress and overlying strata movement.It is necessary for Dongjiahe Coal Mine to restrict the overburden rupture because of its water disasters.However,irregular excavation and overburden geologic tectonics have brought great challenges to the control of the rupture of overlying strata.In this article,the main content is about the stress of the surrounding rock and the movement of the overburden under different mining parameters at different stages of working face mining.Based on the most classical key layer theory,the formation and characteristics of overlying rocks in the face of the strata during the excavation are discussed.The small fault is a common geological structure in Dongjiahe mining area.According to the actual geological conditions of the 22517 working face of Dongjiahe coal mine,the RFPA software is used to simulate the superiority of different mining methods,the results can provide some reference for the coal mining.Then,the FLAC software was used to simulate the rupture and developmental height of the overlying strata in the face of different mining parameters in the 22517 working face of Dongjiahe Coal Mine.At the same time,the ESG company's microseismic monitoring system is installed in the 22517 working face to monitor the rupture zone overburden in a real-time dynamic way.It can provide an early warning for coal mine safety.The main conclusions of this paper are as follows:(1)Under the same condition,when the critical layer is located with upper,the overburden fracture height is less than when the critical layer is located with lower.When the critical layer is located with upper,the height of the overburden fracture increases uniformly with the advancing distance of the working face.When the critical layer is located with lower,the critical layer plays a decisive role in the overall stability of the overburden,and once the underlying key layer breaks,the overlying strata collapses instantaneously.(2)Under the same mining distance,when the hang wall is mined toward the fault,the overburden fracture height is less than when the foot wall is mined toward the fault.At the same time,the stress surrounding the hang wall rock is smaller than the stress surrounding the foot wall rock.(3)The numerical simulation results show that if the mining face is too small,the plastic zone increase slowly and the height is low,and the coal production is obviously limited.The overlying rocks collapse when the mining face is too big and it is easy to induce coal mine safety accidents.Through the microseismic monitoring and numerical simulation comprehensive judgment,we know that 22517 working face overburden fracture height is about 100 m,the face of the overlying rock movement angle is about 67 degrees.The mining face adopts the mining parameter of 4m in height and 200 m in width.It can ensure that the height of the overburden fracture of the working face has a certain safe distance to the surface river.This mining parameters can meet the engineering safety requirements and it will not lead over the old water and the surface river.