Study On Coupling Distribution Law Of Front Stress And Gas Pressure In Coal Mining Face Before And After Water Injection

In this paper,the coupling distribution law of stress field and gas pressure in mining face under the influence of water injection is studied by means of laboratory test,numerical simulation and field test,which is based on the main line of coal seam water injection prevention and control.It is not only of theoretical significance,but also of great practical application value to provide basis for coal seam water injection measures to prevent and control briquette and gas outburst.In order to study the relationship between water absorption rate and time,and the uniaxial mechanical properties of coal samples before and after injection,the natural water absorption rate test was carried out on the coal sample of 17 coal seam in the tenth mine of the Pingdingshan Tianan Coal Industry Co.,Ltd.According to the theory of coal seam gas seepage and the theory of stress deformation of primary rock,and according to the existing research results,combined with the theory of effective stress,adsorption deformation and evolution of the seepage characteristics of the original rock,the interaction between the stress and strain field of gas field and coal rock is coupled,and the relevant mechanical control equation is established,Based on PM double pore medium,the control equation of gas and coal body evolution under mining stress disturbance is established in this paper.Based on the powerful modeling characteristics and mathematical solution ability of COMSOL Multiphysics software,a numerical model is established to simulate the variation of the coupling distribution of ground stress and gas pressure in front of coal mining face before and after water injection,and to reveal the mechanism of concentrated stress forward in front of working face caused by coal seam water injection.The reason is that the water injection seeps into the hole crack of the coal body,infiltrating the coal body,changing the physical and mechanical characteristics of the coal medium,reducing the strength of the coal body,making its support capacity decrease,resulting in the widening of the fracture zone and the unloading zone in front of the working face,reducing the stress peak and moving forward to the deep partThe field test of the ten mines of Pingdingshan Tianan Coal Industry Co.,Ltd.was carried out by using the stress-gas pressure Integrated monitoring system,the ground stress values and gas pressure data were measured,and the variation law of the coupling distribution of the front stress and gas pressure in the mining face before and after water injection was further verified on the spot.