Study And Application Of Deep-hole Coal Seam Water Injection Seepage Model And Outburst Prevention Mechanism

There is coal and gas outburst danger in the process of mining outburst coal seam,which threatens the life and health of workers and the safety of mine production.Based on the research background of ji 15-12070 fully mechanized working face in Shoushan No.1 coal mine,and the implementation of regional outburst prevention measures,in order to further reduce the outburst risk in the mining process,in this thesis,the research methods of theoretical analysis,numerical simulation,laboratory experiment and field test are adopted to study the two-phase seepage law of coal seam water injection and its comprehensive outburst prevention mechanism.The influence law of each influencing factor on the two-phase seepage and outburst prevention of coal seam water injection is determined,and the technical scheme of coal seam water injection outburst prevention in fully mechanized mining face is put forward and field test is carried out.According to the theory of porous media two-phase seepage,the mathematical model of coal seam water injection two-phase seepage in fully mechanized coal mining face is established,and the finite element method is used for numerical simulation.The law of coal seam water injection seepage in "three zones" of working face stress is obtained,and its main influencing factors are determined.The results show that the interface between water and gas is formed after water injection,.and the farther away from the water injection hole,the smaller the two-phase pressure,pressure gradient,seepage velocity gradient and water saturation are.The wetting radius of each stress zone is different.The wetting radius increases in logarithmic function with the increase of water injection pressure and injection time,and decreases in quadratic function with the increase of coal seam gas pressure and solution surface tension.The sealing depth has a great influence on the water injection effect.Using self-made water injection gas adsorption desorption device and other experimental systems,the mechanism of coal seam water injection outburst prevention was studied.The results show that with the increase of coal water content,the parameters such as outburst strength,brittleness coefficient,tensile strength,compressive strength,elastic modulus,Poisson’s ratio,cohesion and internal friction angle decrease,and the gas displacement effect and displacement effect showed quadratic function type enhancement,and the inhibition effect showed logarithmic function type enhancement.The adsorption and storage capacity of coal particles increases with the increase of water injection pressure.According to the results of experiment and numerical simulation,the mechanism of outburst prevention by water injection is revealed.Based on the theory of coal and gas outburst and limit equilibrium,the finite difference method is used to simulate the stress distribution and gas distribution of coal seam in fully mechanized mining face.The results show that with the increase of coal water content,the width of pressure relief zone increases in logarithmic function,the peak stress decreases in power function,the position of peak stress shifts to the depth of coal body,and the stress gradient and average stress value decrease;and under the action of pressure water displacement,the gas content and gas pressure in the water injection area are greatly reduced.Combined with the numerical simulation and experimental results,the technical scheme of water injection for outburst prevention in fully mechanized coal mining face is put forward,and the field test is carried out.After water injection,the wetting radius of each stress zone reaches 2.36～2.59m,the gas pressure in coal decreases by 20.04%～46.56%,the gas content decreases by 53.96%～71.79%,and the outburst risk indexes are all reduced to below the critical value,and good water injection outburst prevention effect is achieved.