煤与瓦斯突出问题制约着对煤炭资源的高效开采，淮南平煤矿区作为松软低透气性且瓦斯含量较高的煤层群开采典型代表，大量实践证明，开采下保护层，并选择合理的抽采卸压瓦斯技术，是对远距离上被保护层卸压增透，并选择合理的抽采卸压瓦斯技术是最行之有效的区域性防治瓦斯手段，。淮南平煤矿区作为松软低透气性且组间层间距大的煤层群典型代表，保护层开采技术在平煤矿区的部分矿井取得较好的效果。

本文以平煤六矿为工程背景，综合应用理论分析、物理相似模拟、数值模拟及现场验证的方法，研究了采场覆岩的裂隙发育规律及卸压范围，分析了在远距离下保护层推进过程中覆岩的位移变形破坏对远距离上被保护层产生的影响以及上被保护层内裂隙的演化规律和基本形态，选择了抽采远程卸压瓦斯的方法提出了上被保护层抽采卸压瓦斯的“时间窗口期”，并并成功运用到工程实践中，为类似地质条件的远距离保护层开采及卸压瓦斯抽采技术提供了理论依据和参考，研究内容如下：进行了抽采卸压瓦斯的工程应用。

通过物理相似模拟实验研究了下保护层采空区上覆岩层移动变形及垮落规律、采动裂隙演化规律及采动裂隙分布规律。通过利用DIC数字照相变形量测系统对实验台监测，覆岩裂隙带最终发育高度为564m，被保护层位于弯曲下沉带，覆岩的应变垮落形状从“扇形”逐渐发展成“等腰梯形”并不断扩大最终上升至模型顶部，影响到远距离被保护层受到保护层开采的影响，并且会在力的作用下发生形变 ；通过对铺设在物理相似模拟实验台内的受扰动型煤进行CT扫描并数据后处理，结果表明位于弯曲下沉带内的远距离被保护层在发生膨胀变形后煤层内主要生成拉伸型横向裂隙，纵竖向裂隙基本不发育。

通过UDEC数值模拟软件研究了在保护层工作面开采后远距离被保护层的应力变化及位移变形情况，覆岩采动裂隙为“马鞍形”分布，在保护层工作面推进至120m时，远距离被保护煤层受到保护层工作面采动的影响，被保护层内有横向裂隙生成。被保护层内的横向裂隙发育随保护层向前推进呈周期性前移，并且被保护层的应力和变形随保护层向前推进呈规律性变化，应力变化总体呈“W”型分布，膨胀变形总体呈“M”型分布，远距离被保护层在卸压范围内任一位置应力变化总体呈“W”型分布，膨胀变形总体呈“M”型分布都经历，分为压缩变形—膨胀变形—膨胀变形增大—膨胀变形减小—趋于稳定的五个阶段。

现场向上布置穿层钻孔抽采远距离上被保护层的卸压瓦斯，保护层工作面推过卸压钻孔16.2~17.2m后迅速上升，此时出现抽采上被保护层卸压瓦斯的“时间窗口期”，并持续到工作面推进过卸压钻孔330~385m之间，持续时间为95天~110天，通过对“时间窗口期”的精准掌握，显著的提高瓦斯抽采率，在保护范围内的上被保护层瓦斯压力降低了1.978MPa，瓦斯含量降低了5.54.205m³/t，有效消除上被保护层的突出危险性。；现场同时向下布置穿层钻孔拦截近距离下被保护层的卸压瓦斯，并对拦截抽采卸压瓦斯初期一个月内的拦截抽采钻孔进行分析，钻孔抽采浓度随天数逐渐增加，拦截效果较好。该研究可为同类型保护层开采卸压瓦斯防治提供一定借鉴，可以有效防治煤层瓦斯突出。

Coal resources support the rapid development of China's economy, but the problem of coal and gas outbursts restricts the efficient mining of coal resources. A large number of practices have proven that mining the lower protective layer and selecting reasonable gas extraction and pressure relief technologies are the most effective regional gas prevention and control measures for The protective layer experiences enhanced permeability and pressure release over significant distances. As a typical representative of the soft, low permeability, and large interlayer spacing coal seam group, the protection layer mining technology has achieved good results in some mines in the Pingnan coal mining area.The Huainanping coal mine area, as a typical representative of coal seam mining with soft, low permeability and high gas content, has been proven by a large number of practices to be the most effective regional gas prevention and control technology by unloading and increasing permeability of the lower protective layer and remotely extracting and releasing gas through reasonable remote extraction. This article takes Pingmei Sixth Mine as the engineering background, and comprehensively applies theoretical analysis, physical similarity simulation, numerical simulation, and on-site verification methods. Due to the long distance between the protective layer and the protected layer, the development law of cracks and the range of pressure relief in the overlying rock of the mining area are studied, An analysis was conducted on the impact of displacement, deformation, and damage of the overlying rock on the long-distance upper protected layer during the advancement of the protective layer, as well as the evolution law and basic morphology of cracks within the protected layer. An appropriate method for remote extraction of depressurized gas was selected, and a "time window period" for the extraction of depressurized gas from the upper protected layer was proposed. The engineering application of the extraction of depressurized gas was also carried out.

This article takes Pingmei Sixth Mine as the engineering background, and comprehensively applies theoretical analysis, physical similarity simulation, numerical simulation, and on-site verification methods to study the development law of fractures in the overlying rock of the mining area. It analyzes the impact of displacement deformation and damage of the overlying rock on the upper protected layer during the long-distance advancement of the protective layer, as well as the evolution law and basic morphology of fractures in the upper protected layer. The method of remote gas extraction and pressure relief has been selected and successfully applied in engineering practice, it offers a theoretical basis and serves as a reference for long-distance protective layer mining and gas extraction under similar geological conditions.  This study provides valuable insights for the industry. The specific research content is as follows:

Through physical similarity simulation experiments, the deformation and collapse laws of the overlying strata in the goaf of the lower protective layer, the study focused on the evolutionary pattern and distribution of mining cracks. Using the DIC digital photography deformation measurement system to monitor the experimental platform, the final development 

height of the overlying rock fracture zone is 54m, and the protected layer is located in the bending and sinking zone. The strain collapse shape of the overlying rock gradually develops from a "fan-shaped" shape to an "isosceles trapezoidal" shape and continues to expand, ultimately affecting the long-distance protected layer; Through CT scanning and data post-processing of disturbed shaped coal laid in a physical similarity simulation test bench, the results showed that transverse cracks were generated in the coal seam after the expansion deformation of ultra-long-range protective layer located in a curved settlement zone, while longitudinal cracks did not develop.

The stress changes and displacement deformation of the long-distance protected layer after mining in the protective layer working face were studied using UDEC numerical simulation software. When the protective layer working face advanced to 100m, the long-distance protected coal seam was affected by the mining of the protective layer working face, and transverse cracks were generated in the protected layer. The stress and deformation of the protected layer show regular changes as the protective layer advances. The overall distribution of stress changes is in a "W" shape, while the overall distribution of expansion deformation is in an "M" shape. At any position within the unloading range, the protected layer at a long distance undergoes five stages: compression deformation, expansion deformation, expansion deformation increase, expansion deformation decrease, and tends to stabilize.

On site, cross layer boreholes are arranged to extract pressure relief gas from the protected layer at a distance. The working face of the protected layer pushes the pressure relief boreholes 16.2-17.2m before rapidly rising. At this time, a "time window period" for extracting pressure relief gas from the protected layer occurs, which lasts for 95-110 days until the working face advances 330m to 385m. By accurately grasping the "time window period", the gas extraction rate is significantly improved, The gas pressure in the upper protected layer within the protection range decreased by 1.9MPa, and the gas content decreased by 4.205m³/t, effectively eliminating the risk of gas outburst in the upper protected layer.