地面钻孔抽放采空区瓦斯及其稳定性分析

随着放顶煤开采技术在我国的迅速普及，采煤工作面及采空区的瓦斯涌出量不断增加。传统的高位钻孔、（本）煤层钻孔及穿层钻孔抽放技术有时不能完全满足现代化煤矿生产对瓦斯抽放的要求。采用地表垂直钻孔抽放采空区内的瓦斯是瓦斯治理技术的另一选择。煤层开采后，采窄区上覆岩层将发生非连续破坏和连续移动。在长壁工作面通过的过程中，地面垂直钻孔可能随岩层移动而发生破坏。据此，介绍一种进行地面抽放采空区垂直钻孔的应用及稳定性分析的方法及用于确定钻孔及套管直径的应用实例。采用提出的计算方法可避免由于受采动影响对地表瓦斯抽放钻孔引起的过大变形及其所造成的破坏。通过计算地表钻孔在不同深度的水平位移和垂直变形可确定钻孔直径和所需安设套管的直径及套管外充填材料的性能。

SURFACE BOREHOLES FOR DRAINAGE OF GOAF GASES AND ITS STABILITY ANALYSIS

As longwall caving technology prevails rapidly in China, gas emission from longwall faces and goaf area increases continuously. Traditional gas drainage techniques, such as drilling roof holes from tailgate or drilling inseam and cross-measure holes, sometimes can not meet the requirements of methane drainage for a modem longwall operation. The alternative method to drill gas drainage holes underground is to drill boreholes from surface to the goaf area. When a coal seam is being extracted out, the upper rock strata above the goaf will be undergoing discontinuous damage and continuous movement. During overlying rock strata being fractured, the surface gas drainage boreholes may be damaged due to ground movement. A method for the calculation of the stability of surface boreholes for drainage of gas from goaf area is introduced. An example of determination of borehole and casing diameters is given to demonstrate the application of the computational method. By using this method, the damage of surface gas drainage holes caused by induced excessive mining displacement can be effectively reduced if not being avoided. Surface borehole diameter and casing diameter as well as characteristics of filling materials can be achieved by calculating the horizontal movement and vertical stain at different depths.