Study on advancing speed effect of pressure relief gas transport and storage area evolution in fully mechanized mining face

In order to study the evolution law of gas transportation and storage area under different advancing speed of fully-mechanized working face, based on the overview of coal mine project, we analyzed the effect of overburden mining advancing speed by using FLAC^3D numerical software for simulation, and used various methods to jointly discriminate the unloading gas transportation and storage area, obtained the distribution and evolution law of unloading gas transportation and storage area under different advancing speed conditions. Based on this, we optimized the high level extraction drilling in the field. The results show that after the coal seam mining in the fully mechanized mining face, the vertical stress distribution roughly follows a symmetrical trapezoidal shape, and the advancing speed is accelerated. The vertical stress distribution changes into a left high right low throw line; the subsidence amount and plastic failure height of the overlying rock in the goaf decrease with the increase of advancing speed; the height of the unloading gas storage area decreases with the increase of the advancing speed, and the location of the unloading gas storage area is concentrated towards the middle of the goaf; after optimizing the pressure relief gas extraction drilling holes in the experimental working face, the maximum gas volume fraction of the extraction drilling holes in the high and low advancing speed areas of the experimental working face is above 30%. The gas volume fractions in the working face, return air roadway, and upper corner are 0.18%-0.46%, 0.2%-0.46%, and 0.25%-0.84%, all less than 1%, making the layout method more reasonable.