Study on Gas Migration Mechanism and Multi-Borehole Spacing Optimization in Coal under Negative Pressure Extraction

In order to study the gas migration in gas-bearing coal, and reasonably arrange drainage boreholes improve efficiency of drainage, a gas-solid coupling model is established based on pore-fracture dual medium porous model. The solid deformation coal body, seepage diffusion, adsorption desorption are considered this COMSOL software used simulate change matrix fracture under single borehole extraction. We analyze effective extraction range mechanism between borehole, fracture, matrix. area multi-borehole negative pressure varies with time spacing. At 140 d, radius r = 1.3 m, spacing 233 r=1.5 2 r=2.6 m,4 m,5 m,and 6 respectively. influence equilateral triangle shape three effect studied. simulation results show that when extracted for days different spacing, effects will be affected by superposition effect. Considering pressure, area, safety cost performance extraction, it concluded optimal hole 5 m around d. This aims provide reference underground drilling layout reasonable