深部煤层瓦斯抽采钻孔变形失稳区域研究

Study on deformation and instability area of deep coal seam gas drainage boreholes

深部开采煤层具备“三高一低”特性,抽采钻孔在深部煤层施工时及抽采过程中极易发生喷孔、塌孔等现象。采用数值模拟分析了不同部位抽采钻孔的变形失稳情况,确定了易发生变形失稳区域;根据弹塑性软化理论模型,研究了巷道围岩裂隙区和塑性区半径的变化规律,确定了钻孔位于巷道围岩内9.28 m左右区域容易发生失稳坍塌;现场实际钻孔变形失稳影响因素众多,钻孔失稳坍塌的部位亦有所不同。研究成果对钻孔失稳坍塌区域的准确防护、进而解决深部开采煤层抽采钻孔失稳坍塌问题有着重要的现场指导意义。

The deep mining coal seam has the characteristics of"three high and one low".During the construction and extraction process of the deep coal seam,it is very easy to have such phenomena as shotcrete hole and hole collapse.The deformation and instability of the pumping boreholes in different parts were analyzed numerically,and the regions of deformation and instability were determined.According to the elastic-plastic softening theoretical model,the changing rules of the fracture zone and the plastic zone radius of the roadway surrounding rock were studied,and it was determined that the area where the borehole was located in the surrounding rock of the roadway was prone to instability collapse within the range of 9.28 m.There are many factors affecting the deformation and instability of borehole in the site,and the location of borehole instability and collapse is also different.The research results have important field guiding significance for accurate protection of borehole unstable collapse area and solving the problem of borehole unstable collapse in deep mining.