我国煤炭开发已逐渐进入深部阶段，“三高一低”特点越来越突出，尤其低渗透性，采用常规瓦斯抽采手段效率较低，需要进行增透煤层瓦斯抽采。水力割缝技术作为一种高效增透技术被广泛采用。然而，在水力割缝中不同煤质、不同层高煤层如何设置合理的割缝参数、布置方式尤为重要。为解决这一问题，论文通过数值模拟分析了不同水射流参数破煤深度，研究了不同割缝参数卸压增透效果，开展了水力割缝工程实践，研究了适合于目标煤层的合理割缝工艺参数及工艺流程。

针对不同割缝参数水射流破煤深度问题，提出不同驱动水压、喷嘴直径水射流破煤深度预测模型。通过Fluent数值模拟软件，建立气—液两相流模型，模拟了不同驱动水压、喷嘴直径水射流速度场，通过准静态破岩模型得到不同参数水射流破煤深度，进一步确定出水力割缝使用的驱动水压、喷嘴直径。

通过FLAC^3D数值模拟，利用单一控制变量法及响应面试验方法，研究不同缝槽直径、钻孔倾角对煤体卸压影响规律，分析缝槽对煤体卸压的力学机制。分析缝槽直径、宽度及钻孔倾角对于煤体卸压范围的交互影响，确定最佳缝槽参数及钻孔间距。

确定了水力割缝增透煤层现场试验方案和设备选型，试验过程中收集时段出煤量数据，研究不同喷嘴直径、水压、割缝时间对割缝出煤量的影响，确定了不同割缝水压、喷嘴直径条件下的破煤深度，分析了水力割缝抽采瓦斯效果及防突效果。试验结果表明，使用设置的割缝参数进行水力割缝后，水力割缝钻孔瓦斯抽采纯量提高了3.5~9.5倍，掘进工作面瓦斯浓度最大值下降40%以上。瓦斯抽采效率明显提升，现场消突效果良好，缩短了煤层瓦斯预抽时间，为工作面瓦斯防治提供了一定理论依据及工程实践参考。

China's coal development has gradually entered the deep stage, the characteristics of "three high and one low" are more and more prominent, especially the low permeability, the efficiency of conventional gas extraction means is low, it is necessary to carry out anti-reflection coal seam gas extraction. Hydraulic slotting technology is widely used as an efficient anti-reflection technology. However, how to set reasonable seam parameters and arrangement mode is particularly important for different coal quality and different layer coal seams in hydraulic seam cutting. In order to solve this problem, the paper analyzed the coal breaking depth with different water jet parameters through numerical simulation, studied the effect of pressure relief and reflection improvement with different slit parameters, carried out hydraulic slit engineering practice, and studied the reasonable slit parameters and process flow suitable for the target coal seam.

Aiming at the coal breaking depth of water jet with different slit parameters, a prediction model for coal breaking depth of water jet with different driving pressure and nozzle diameter was proposed. The gas-liquid two-phase flow model was established by Fluent numerical simulation software, and the velocity field of water jet with different driving water pressure and nozzle diameter was simulated. The coal breaking depth of water jet with different parameters was obtained by quasi-static rock breaking model, and the driving water pressure and nozzle diameter used for hydraulic cutting were further determined.

Through FLAC3D numerical simulation, single control variable method and response surface test method, the influence law of different slot diameters and drilling inclination Angle on coal pressure relief was studied, and the mechanical mechanism of slot pressure relief was analyzed. The interaction effects of slot diameter, width and drilling Angle on coal pressure relief range are analyzed, and the optimum slot parameters and drilling spacing are determined.

Determine the hydraulic slotted anti-reflection coal field testing scheme and equipment type selection, test process in the coal quantity data collection period, different nozzle diameter, water pressure, slotted time slot on the influence of coal, identified the different slot depth of water pressure, nozzle diameter under the condition of the coal, analyses the hydraulic cutting seam extraction gas effect and the outburst prevention effect. The test results show that the pure gas extraction amount of hydraulic slit drilling increases by 3.5~9.5 times, and the maximum gas concentration of driving face decreases by more than 40% after hydraulic slit is used. The gas extraction efficiency is obviously improved, the effect of on-site outburst elimination is good, and the pre-extraction time of coal seam gas is shortened, which provides a certain theoretical basis and engineering practice reference for gas prevention and control in working face.

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