密集钻孔周围透气性与加载应力关系的模型实验

Model Experiment about Relationship between Permeability around Dense Borehole and Loading Stress

密集钻孔预抽瓦斯防止煤与瓦斯突出已在煤矿中得到应用，瓦斯抽采率与钻孔间距和煤层的透气性密切相关，应用物理模拟实验，以达西定律为测定理论，在不同载荷应力作用下，对2种不同的钻孔直径和间距进行了透气性考察；实验表明，用小直径和大间距的钻孔，其周围透气性随着加载应力的增大而减小，用大直径和小间距的钻孔，最近钻孔测点的透气性随着加载应力的增加而增大，增透半径约为0．8～1．0倍的钻孔直径；离钻孔较远的测点的透气性随着加载应力的增加而减小。

The method of gas preliminary drainage by drilling densc boreholes, which can prevent coal and gas outburst, has been used in coal mine. The gas extraction rate is related to the boreholes gap and the permeability of the coal seam. In the model experiment, two kinds of cases with different borehole diameter and gap are studied under different loading stress according to the Darcy law. The results show that the permeability around the boreholes with small diameter and big space decreases with the loading stress increasing, whereas around the boreholes with big diameter and small space, the permeability of the closest test points increases with the loading stress increasing. The enhancing permeability radius is about 0. 8 - 1.0 time to the borehole diameter. The permeability of the test points far from the borehole decreases with the loading stress increasing.