厚表土层深井卸压开采地面钻井变形破坏及其预防——以淮南顾桥矿为例

以顾桥矿工程实践为基础，结合物理模拟实验和现场监测结果，研究了厚表土层深井卸压开采地面钻井变形破坏及其预防。结果表明:钻井破坏是地面卸压瓦斯抽采失败的关键，采动影响下地面瓦斯抽采井破坏以变形和错断为主，破坏深度不一，主要集中在松散层中下部和基岩中上部；在钻井完好情况下，将钻井终孔位置布置于断层附近、“O”型圈范围内更有利于卸压瓦斯抽采。采动引起的上覆岩层离层、应力集中、竖向破断以及厚表土层“杠杆效应”造成地面瓦斯抽采井破坏，其由下至上多次出现是导致地面井多处变形破坏的主要原因。煤层采动对工作面前方巷帮应力、顶板应力的影响范围分别可达320 m、350 m，对轨顺相对位移影响范围可达工作面前方50m和后方200m，采场中部覆岩与地表之间的相对位移量远大于采场边缘附近，更容易导致井孔破坏。采用“抗”和“让”相结合的井身结构、“上止下泄”固井–完井施工工艺以及合理的井位布置等措施，可有效防止卸压开采地面钻井变形破坏，实现瓦斯稳定高效抽采。 

Deformation and damage of pressure-relieved gas extraction wells in deep mining under thick surface soil and their prevention: With Guqiao of Huainan mine as an example

Based on the engineering practice of Guqiao coal mine, combining with the physical simulation experiment and field monitoring results, the deformation and damage failure of surface drilling for deep well pressure relief mining and their prevention in thick alluvium were studied. The results show that drilling damage is the key factor for the damage of ground pressure relief gas extraction. Under the influence of mining, the damage of the surface gas extraction well is mainly deformation and fault section, and the damage depth is different, mainly concentrated in the middle and lower part of the loose layer and the middle upper part of the rock. In the condition of well drilling and completion, the end hole position of the drilling well is arranged near the fault and "O"-type ring is more conducive to pressure relief gas drainage. The overlying strata separation, stress concentration, vertical breakage and the "lever effect" caused by the overlying strata caused the destruction of the surface gas extraction well, and this phenomenon occurs from the bottom to the top many times, which is the main cause of the deformation and damage of the surface wells. The influence of coal mining on the stress of roadway and roof in front of the working face can reach 320 meters and 350 meters respectively, the influence of relative displacement on the track can reach 50m in front of the working face and 200m in the rear. The relative displacement in the middle of the stope is much larger than that at the edge of the stope, which is more likely to lead to drilling damage. By optimizing the well structure, improving the cement-completion construction technology and reasonable well location layout, it can effectively prevent the deformation and damage of the surface drilling in pressure relief mining and achieve stable and efficient gas extraction.