Study On Stress Characteristics And Energy Locking Effect On Outburst Of Structural Coal Seam Variation Zone In Pingdingshan No.10 Coal Mine

Geological tectonic movement can change the physical and mechanical properties of coal,reduce the strength of coal,and then change the gas occurrence and stress distribution in coal.Under the action of strong horizontal tectonic stress,the coal seam and weak strata will have plastic rheology,which leads to serious deformation of the coal seam and roof and floor,and changes of the coal seam thickness.The coal thickness change zone is the high incidence area of coal and gas outburst accidents,in order to explore the mechanism of coal and gas outburst in the coal thickness change zone,this paper takes Pingdingshan No.10 coal mine as the research background,through theoretical analysis,laboratory research and numerical simulation,the distribution law of regional tectonic stress field in Pingdingshan No.10 coal mine is determined.Combined with the case study of specific outburst accident,the stress distribution and energy enrichment law of coal thickness variation zone are analyzed,and the theory of roadway excavation technology in structural coal seam thickness variation zone is put forward.The research methods and conclusions are as follows:（1）Two groups of coal samples were taken from the Ji coal seam with the most serious outburst risk to measure the multi physical parameters and analyze the pore structure in the laboratory.The firmness coefficients of the two groups of coal samples are 0.35 and 0.28 respectively,the initial velocity of gas emission is 13.05mm Hg and15.25mm Hg respectively,The micropores and mesopores in the two groups of coal samples are developed,and both of them have outburst risk.（2）According to the data of seven in-situ stress measuring points in the mine,the regional in-situ stress field is inversed by FLAC^3D,the lateral pressure coefficient of the measuring points is 1.44～2.65,and the average value is 1.91,which indicates that the horizontal tectonic force is the dominant tectonic stress field in No.10 mine.The inversion results show that there is stress concentration in the axis of syncline,and the maximum horizontal principal stress can reach 74.6MPa,while there is slight stress release in the axis of anticline.（3）Based on the outburst accident in the air lane of Ji_15-16-22230 working face,the model of coal thickness variation zone is established,the stress distribution and energy enrichment law of coal thickness variation zone are studied,and the stress concentration and energy enrichment area of coal seam and floor rock in coal thickness variation zone are determined.The meso mechanical properties of tectonic coal under different confining pressures are simulated by EDEM,the results show that the coal will appear strain hardening under high stress conditions,and more energy can be accumulated inside.（4）Through the simulation of roadway excavation,the distribution law of advance stress and energy of coal in front of working face during excavation is studied.When driving to 21m,the advance abutment pressure and energy of coal reach the peak value,the peak value of stress is 27.89MPa,and the peak value of energy density is 119.2k J/m³.At this time,the outburst risk of coal is the largest.There are 61 pictures,13 tables and 84 references in this paper.