深厚表土地区地面瓦斯抽排钻孔套管设计

Design of Ground Gas Drainage Borehole Casing in Deep Alluvium Region

为了研究深厚表土地区地面瓦斯抽排钻孔套管设计,从模型的建立、套管工作荷载的选取、套管稳定性计算公式选择等方面进行了研究。结果表明:从永久使用方面考虑,套管受力模型和钻井法井壁相似,故可参考钻井法井壁结构设计,对其使用阶段所受的荷载进行考虑;根据薄壁圆筒理论,从受力的角度分析指出瓦斯抽排钻孔套管使用高强度钢材不合理;从受力和施工等方面考虑,深厚表土地区地面瓦斯抽排钻孔护壁套管和工作套管的安全系数应进行不同考虑。

Aiming at the design of ground gas drainage borehole casing in the deep alluvium region, this paper analyzed the model establishment, and the selection of working load of borehole casing and calculation formula for casing stability. The results show that ： as the casing is for permanent use, the mechanical model is similar to shaft wall in shaft boring, to which the design can reference to consider the loads in different service stage; according to the thin - walled cylinder theory, using high - strength steel pipe is mechanically unreasonable in gas drainage borehole casing; and from the views of stress distribution and construction, the safety factor of protection casing and working casing should be considered differently, for the ground gas drainage borehole in the deep alluvium region.