我国煤矿瓦斯灾害防治对策

由于钻孔排渣空间狭小、煤体颗粒易堆积等原因，顺层钻孔在水力割缝过程中容易出现喷孔、堵孔及抱钻等现象，严重影响顺层钻孔割缝施工成功率及安全性。针对以上问题，研究了顺层割缝钻孔钻进时的钻孔形态，通过分析钻孔下沉现象，将割缝钻孔分为加速下沉段、倾斜下沉段及开孔段3个阶段，分析了各阶段钻孔堵孔模型及堵孔现象。研究得到割缝钻孔各阶段煤渣的运移情况：加速下沉段钻孔煤渣运移以水流升力及拖拽力为主，煤水混合两相流体通过钻杆旋转的扰动作用充分混合；倾斜下沉段则以钻杆外螺旋旋转动力为主带动煤渣运移。通过大量现场试验，得到了不同煤层坚固性系数条件下的割缝压力及钻杆转速参数。研究发现，随着煤层坚固性系数的增大其最优割缝压力随之增大，但合理钻杆转速随之减小，形成了包括合理选择割缝压力及钻杆转速参数、控制压力调节梯度、孔口返水返渣情况观测，以及延长割缝后低压洗孔时间等4个方面措施的顺层钻孔割缝排渣工艺技术。现场试验结果表明，割缝排渣工艺技术能有效避免割缝堵孔风险，保障顺层钻孔割缝安全实施，提高割缝成功率，大幅提高钻孔瓦斯抽采效率，有效推进了顺层钻孔水力割缝卸压增透技术的应用。

Cross-borehole hydraulic slotting technique for preventing and controlling coal and gas outbursts during coal roadway excavation

Due to the narrow slagging space of drilling and the easy accumulation of coal particles, it is easy to cause the phenomena of jet hole, hole plugging and holding drill in the process of hydraulic slotting in drilling along coal seam, which seriously affects the success rate and safety of slotting construction in drilling along coal seam. In view of the above problems, the drilling shape of slotting drilling in drilling along coal seam was studied.By analyzing the phenomenon of drilling subsidence, the slotting drilling was divided into three stages: accelerated sinking section, inclined sinking section and opening section. The phenomenon of drilling plugging model and hole plugging in each stage were analyzed. The coal cinder movement in each stage of slotting drilling was studied. It is obtained that the coal cinder movement in the accelerated sinking section is dominated by water lift and drag force, the coal and water mixed two-phase fluid is fully mixed through the disturbance of drill rode rotation; in the inclined sinking section, the external spiral rotation power of the drill rode is the main driving force to drive the movement of coal cinder. Through a large number of field tests, the parameters of slotting pressure and drill rode speed under different coal seam conditions of firmness coefficient are obtained. It is concluded that with the increase of coal seam firmness coefficient, the optimal slotting pressure increases, but the reasonable drill rode speed decreases, the technology of slotting slag discharge in drilling along coal seam has been formed, which includes reasonable selection of slotting pressure and drill rode speed parameters, control of pressure adjustment gradient, observation of water and slag return at orifice, and extend the time of low-pressure hole washing after slotting. The field test shows that the technology of slotting slag discharge can effectively avoid the risk of slotting and hole plugging, ensure the safe implementation of slotting in drilling along coal seam, improve the success rate of slotting, greatly improve the effect of drilling gas drainage, and effectively promote the application of the technology of hydraulic slotting and antireflection and pressure relief in drilling along coal seam.