Research On The Breaking Law Of The Overlying Rock In The High-stress Working Face Of Yuwu Coal Industry

At present,with the gradual depletion of shallow coal resources,most of Chinese coal mines have gradually entered the deep mining stage.However,due to the complex geological conditions of coal mines,the difference in coal seam depths is large,the ground stress is high,the roof movement law is unclear,and the overlying strata are transported.Factors such as migration activity have had a serious impact on coal mining.Taking Yuwu Coal Industry of Shanxi Lu'an Group as an example,the buried depth of the coal mining in this mining area is generally more than 500 m,and the stope stress is high,and there is a lack of comprehensive understanding of the process of overburden rock activity on the roof of the stope.Therefore,based on the mining geological conditions of Yuwu coal mining face,this paper uses a comprehensive research method combining field investigation,laboratory experiment,theoretical analysis,numerical simulation,and field measurement to study the breaking law of the overburden of Yuwu high-stress roof.The main research results of this paper are as follows:(1)Analyzed and summarized the geological conditions of Yuwu Coal Industry,and carried out physical and mechanical parameter tests of coal and rock masses to obtain the uniaxial compressive strength,tensile strength,and shear strength of coal,sandy mudstone,and siltstone.Parameters provide basic data for mechanical calculations and numerical simulations.(2)Based on the calculation of beam mechanics model,the initial pressing step distance and the periodic pressing step length of the target working face of Yuwu Coal Industry are calculated.Based on the basic roof thickness plate model theory,the initial breaking stress state of the basic roof above the working face is analyzed.According to the theory of the thick plate model,the initial breaking step of the basic roof of the working face is obtained by analysis.On this basis,the layer position of the key layer of the roof overburden is analyzed and judged.(3)With the aid of 3DEC numerical simulation software,the fracture characteristics of the overburden rock during the mining face were studied,and the change characteristics of related parameters such as the stress,strain and crack development degree of the overburden rock in different stages were analyzed.(4)Establish a microseismic monitoring system based on the microseismic monitoring technology to monitor the overlying rock activity during the mining face,obtain the distribution of microseismic events in different time periods of the stope,and analyze the overall spatial distribution of microseismic events during the monitoring period status.(5)Comprehensively analyze the microseismic data in the monitoring results to obtain the leading and lagging impact range distributions of the impact of mining on the roof overlying rock.Based on the distribution characteristics of microseismic events in the vertical direction,combined with the geological occurrence of the working face The development height of the fissure zone in the working face.The relative active degree of the overlying rock on the sides of the two roadways in the working face is studied.(6)By analyzing the periodic evolution mechanism of overburden cracks based on microseismic events and location distribution and the spatial dynamic evolution characteristics of microseismic events under the influence of mining,the periodic breaking laws of overburden cracks in the working face are summarized,and the periodicity of the working face is obtained.Pressure step and height of caving zone.Combined with the distribution characteristics of microseismic events over the entire strike length,the activity level of the roof before and after the periodic compression is analyzed.The subject comprehensively uses analysis and research methods such as field investigation,laboratory experiment,theoretical analysis,numerical simulation,field measurement,etc.,to investigate the breaking law of overlying strata in the high-stress roof face of Yuwu Coal Industry of Lu'an Group from multiple angles.The research has obtained the key layer position in the overburden of the working face,the initial collapse step of the basic roof,the periodic collapse step,the height of the stope fissure zone and other characteristic parameters that have key significance for the safe mining of the working face.The research results can be used for the guidance and reference of measures such as roof management,surrounding rock control,mine outburst prevention,have very positive practical significance for ensuring safe and efficient mining of mines and preventing roof accidents.