针对高瓦斯综采工作面U型通风条件下上隅角瓦斯超限问题，分析了定向钻孔代替尾巷抽采卸压瓦斯的必要性及可行性，阐述了卸压瓦斯抽采原理；利用物理相似模拟及理论分析，分析了采动覆岩裂隙演化规律，确定了定向钻孔参数，并进行现场工程应用。结果表明：随着工作面推进，试验工作面采动覆岩形成不规则冒落带、规则冒落带、裂隙带、弯曲下沉带，其中规则冒落带高度为17.9 m（采高的4.48倍），裂隙带高度为60.36 m（采高的15.09倍）；定向钻孔与回风巷平距为8～20 m，与煤层顶板垂距平均18.5 m；利用定向钻机施工钻孔偏移量较小，定位准确，瓦斯抽采纯量平均6.37 m³/min，占瓦斯涌出量的8.59%，实现了定向钻孔代替尾巷治理瓦斯效果，保证了工作面安全回采。 

In view of the problem of gas overrunat the upper corner under the condition of U-shaped ventilation in gassy fully-mechanized mining face, the necessity and feasibility of directional drilling replacing tailgate drainage and pressure relief are analyzed, and the principle of relieved gas drainageis expounded. With physical simulation and theoretical analysis, the evolution law of mining-induced fracture in mining overburden is analyzed, the directional drilling parameters are determined, and the field engineering application has been carried out. The results show that as the working face advances, the mining face of the test working face forms irregular caving zone, regular caving zone, fracture zone and continuous bending deformation zone in the overburden of the test working face. The height of regular caving zone is 17.9 m (4.48 times of the mining height), and the height of fracture zone is 60.36 m (15.09 times of mining height). The horizontal distance between the directional drilling and the return air roadway is 8～20 m, and the average vertical distance between the drilling and the coal roof is 18.5 m. Directional drilling rig has been used to construct drilling with small offset and accurate positioning. The average gas drainage volume is 6.37 m3/min, accounting for 8.59% of the gas emission. The effect of directional drilling instead of the tailgate gas treatment has been achieved to ensure safe mining in the working face.