基于动态流固耦合模型的瓦斯抽采半径及孔间距研究

Study on gas drainage radius and distance between boreholes based on dynamic fluid-solid coupling model

为了确定瓦斯抽采半径和钻孔布置间距,基于上覆岩层压力、地应力、煤层瓦斯压力的分布情况,同时考虑煤体剪胀性对于煤体孔隙率、渗透率动态变化方程的影响,建立了关于钻孔瓦斯抽采的渗流动态流固耦合模型。基于所得渗流流固耦合模型,将其嵌入到Comsol Multiphysics进行模拟计算,同时利用11528工作面进行的单孔和多孔的瓦斯抽采试验进行现场验证。研究结果表明:沿直线布置的抽采钻孔的瓦斯压力变化主要沿着该直线降低,沿着三角形顶点布置的钻孔瓦斯压力降低范围充满整个半圆面;单孔瓦斯抽采半径为2.05 m,双孔抽采和布置在一条直线多孔抽采布控间距为单孔抽采半径的1.8倍;布置在三角形顶点的多孔抽采布控间距为单孔抽采半径的1.6倍。

In order to set up the gas drainage radius and the layout distance between boreholes,based on the overburden strata pressure,geostress and seam gas pressure distribution condition and to consider the coal dilatancy affected to the coal pore ratio and the permeability dynamic variation equation,a seepage dynamic fluid-solid coupling model of the borehole gas drainage was established. Based on the seepage fluid-solid coupling model obtained,the model was embedded in the Comsol Multiphysics for the simulation calculation and No.11528 coal mining face was applied to the site approval on the single borehole and multi borehole gas drainage experiments. The study results showed that the gas pressure variation in the gas drainage borehole along the straight line distribution mainly would be reduced along the straight line and along the delta top layout,the borehole gas pressure reduction range would be a full semicircle. The single borehole gas drainage radius was 2.05 m and a layout distance of the single borehole gas drainage and the multi boreholes layout along the straight line was 1.8 times longer than the single borehole gas drainage radius. The layout distance of the multi boreholes at the delta top points would be 1.6 times longer than the single borehole gas drainage radius.