针对西部地区侏罗系地层煤矿立井钻井法施工中出现的气举反循环洗井排渣与钻进效率低下问题，以陕西可可盖煤矿中央回风立井ϕ4.2 m超前钻井为工程背景，基于CFD-DEM(计算流体力学和离散单元法耦合)研究方法，建立了气−液−固多相耦合排渣数值模型，揭示了排渣管内、井底流场的速度及压力分布规律，并基于自研的气举反循环排渣试验装置，采用PIV(粒子图像测速法)测试技术对流场分布的正确性进行验证；提出了优化刀盘吸渣口评判指标和方法，对吸渣口的数量、长径比、面积比、总面积占比进行优化，得到了超前钻头刀盘吸渣口布置的最佳方式和相关参数；讨论了钻头转速、注气量、风管没入比和泥浆黏度等主要因素对排渣流场的影响。研究结果表明：① 排渣管内流体的运移以轴向流动为主，且途经注气端时，流速发生跳跃式剧增；井底流体的运移主要以水平流动为主，流体的垂直上返仅存在于吸渣口附近；井底流体的水平流动以切向流动为主，径向流动仅在吸渣口两侧较为明显，且远离吸渣口处，径流速度较小易产生岩屑沉积；② 当刀盘吸渣口数量为2，长径比为0.4，面积比为1，总面积占比为1.94%时，吸渣口的布置方式最佳，且清渣率较现行吸渣口布置方式提高66%；③ 增大钻头转速可显著增强吸渣口的吸附作用，注气量、风管没入比与井底和排渣管内流体的轴向速度均呈正相关关系，低黏、低密度的泥浆易获取高流速，但携岩能力较差。研究结果可为破解侏罗系地层深大立井钻井法洗井排渣与钻进效率低下技术难题，提供有益的理论参考。

Aiming at the problems of gas lift reverse circulation shaft washing slag discharge and low drilling efficiency in the application of vertical shaft drilling method in the Jurassic strata coal mines in western China, taking ϕ4.2 m advanced drilling of central return air shaft in the Kekegai coal mine as the engineering background, based on the CFD-DEM (computational fluid dynamics and discrete element method coupling) research method, a gas-liquid-solid multiphase coupling slag discharge numerical model is established, which reveals the velocity and pressure distribution law of the flow field in the slag discharge pipe and the bottom hole. Based on the self-developed gas lift reverse circulation slag discharge test device, the correctness of the flow field distribution is verified by PIV (Particle Image Velocimetry) test technology. The evaluation index and method of optimizing cutter head suction port are put forward. The number, length-diameter ratio, area ratio and total area ratio of slag suction outlets are optimized. The best way and related parameters of cutter head suction port arrangement of advanced bit are optimized. The effects of main factors such as bit speed, gas injection rate, submerged ratio of air duct and mud viscosity on slag discharge flow field are discussed. The research results show that ① the fluid in the slag discharge pipe mainly moves in the axial direction, and when passing through the gas injection end, the velocity increases sharply. The migration of bottom hole fluid is mainly horizontal flow, and the vertical upward flow of fluid only exists near the slag suction port. The horizontal flow at the bottom of the shaft is mainly tangential flow, and the radial flow is obvious only on both sides of the slag suction port, and it is far away from the slag suction port, so the runoff speed is small and it is easy to produce cuttings deposition. ② When the number of slag suction ports of cutter head is 2, the length-diameter ratio is 0.4, the area ratio is 1, and the total area ratio is 1.94%, the layout of slag suction ports is the best, and the slag removal rate is increased by 66% compared with the current layout of slag suction ports. ③ Increasing the bit speed can significantly enhance the adsorption of the slag suction port. The gas injection rate and the submerged ratio of the air duct are positively correlated with the axial velocity of the fluid in the bottom hole and the slag discharge pipe. The mud with low viscosity and low density is easy to obtain high return velocity, but its rock carrying capacity is poor. The research results can provide a useful theoretical reference for solving the technical problems of washing, slag removal and low drilling efficiency of deep and large vertical shaft drilling in the Jurassic strata.