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鄂尔多斯地区的煤层埋藏浅,表土层厚度对地表漏风影响明显,继而导致采空区的自燃危险区域发生变化。为此以某煤矿4201工作面为研究对象,先通过二维离散单元程序UDEC模拟确定地表与采空区连通时的表土层厚度范围,再根据该模拟结果建立不同表土层厚度条件下的采空区漏风模型,用Fluent数值模拟软件对采空区自燃危险区域进行模拟。结果表明:当采空区上覆基岩厚度一定、表土厚度小于74 m时,煤层开采后地表裂隙会与采空区连通,从而导致地表漏风;表土层厚度越小,采空区自燃危险区域的范围和地表漏风量就越大,两者近似呈对数函数关系;地表漏风不但使采空区自燃危险区域的范围明显增大,而且使回风侧宽度大于进风侧宽度。
The coal seam in the Ordos area is shallow and the thickness of topsoil has a significant effect on surface air leakage, which in turn causes the spontaneous combustion danger area of the goaf to change. In this paper, a coal mine 4201 working face is taken as the research object. The surface soil thickness range when the surface is connected with the goaf is determined by two-dimensional UDEC discrete element program. Based on the simulation results, the mined-out Area air leakage model, using Fluent numerical simulation software to simulate the danger zone of spontaneous combustion in the goaf. The results show that when the thickness of bedrock overlying gob area is constant and the surface soil thickness is less than 74 m, the surface fissures will be connected with the gob area after coal mining, resulting in air leakage on the surface. The smaller the surface soil thickness is, the more spontaneous combustion danger zone The larger the area and the amount of air leakage on the surface are, the two are approximately logarithmic functions. The surface air leakage not only significantly increases the range of spontaneous combustion danger zones in the goaf, but also makes the width of the return air side wider than the width of the inlet side.