厚硬顶板煤层在我国分布极为广泛，该类顶板厚度大、强度高，完整较好，待工作面回采后难以及时垮落，易形成大面积悬顶，致使巷道煤柱内聚集较大的侧向应力，进而导致巷道煤柱发生变形，影响工作面的安全高效生产。对此，本文以小保当一号煤矿112203工作面厚硬顶板为研究对象，结合理论分析、岩石结构力学实验、数值模拟和现场观测等方法，通过系统研究工作面顶板赋存特征和矿压显现规律，在顶板分类的基础上，揭示厚硬顶板水力压裂切顶卸压机理和方法，主要成果如下：

（1）基于工作面顶板岩层结构的差异性，根据直接顶厚度、来压步距和裂隙发育程度等指标对顶板进行分类，明确不同类型顶板的赋存特征和矿压显现规律。同时依据关键层理论，对厚硬顶板关键层进行分析。

（2）建立了厚硬顶板岩层承压结构力学模型，探究了厚硬顶板在开采条件下的承载特征和破断失稳特征。基于载荷估算法对切顶卸压前后巷道煤柱的承载状态进行对比分析，揭示了采用切顶卸压方式处理厚硬顶板，缓解围岩变形的作用机理。并在此基础上，对不同类型顶板进行切顶工艺参数设计。

（3）结合112203工作面厚硬岩层条件，采用UDEC数值模拟方法分析不同切顶角度和切顶高度对顶板卸压效果的影响。同时采用FLAC^3D数值模拟软件对不同切顶钻孔间距对厚硬岩体的弱化损伤情况进行探讨。通过对比分析不同方案下的应力演化规律和覆岩运移情况，给出适合不同类型顶板的最优切顶卸压方案参数。

（4）基于112203工作面实际地质条件，通过以顶板分类为前提，水力压裂卸压为中心的厚硬顶板切顶卸压技术与方法，设计适用于本工作面的水力切顶卸压方案。现场应用结果表明，与未压裂区相比，切顶卸压区域围岩应力平均减小了50.02%，顶底板位移量平均减小了52.87%，两帮移近量平均减小了46.36%，有效改善了巷道煤柱的稳定性，为大采高工作面厚硬顶板控制问题提供了理论参考。

With the increasing intensity of coal mining, large mining face is also becoming more and more common, coupled with the increasing mining depth, the coal seam roof conditions encountered are more and more complex, mining process encountered thick hard type roof is one of them, because of the thickness of this type of roof, high strength, integrity is better, to work after the face back to not easy to timely collapse, resulting in a large area of overhanging roof, so that the coal column of the roadway will gather a large lateral stress This will lead to the deformation of the coal column roadway. In this paper, taking the thick hard roof of 112203 working face of Xiaobodang No. 1 coal mine as the research object, combining theoretical analysis, rock structure mechanics experiments, numerical simulation and field observation, through systematic research on the fugitive characteristics of the roof of the working face and mineral pressure manifestation characteristics, on the basis of the classification of the roof, the mechanism and method of fracturing and unloading the thick hard roof are revealed. The main results are as follows:

Based on the variability of the top structure of the working face, the top slab is classified according to the direct top thickness, incoming pressure step and fracture development degree and other indicators to clarify the fugitive characteristics and mineral pressure manifestation characteristics of different types of top slabs. At the same time, based on the key layer theory, the key layer of the thick hard top plate is determined.

A mechanical model of the pressure-bearing structure of the thick hard roof slab was established, and the bearing characteristics and breaking instability characteristics of the thick hard roof slab under mining conditions were investigated. Based on the load estimation method, the load-bearing state of the coal column in the roadway before and after the top cutting and decompression is compared and analyzed, revealing the mechanism of using the top cutting and decompression method to deal with the thick hard roof slab and relieve the deformation of the surrounding rock. And on this basis, the design of roof cutting process parameters for different types of roof slabs is carried out.

Combining with the thick and hard rock conditions of 112203 working face, UDEC numerical simulation method was used to analyze the effect of different top cutting angle and top cutting height on the pressure relief effect of the roof. At the same time, FLAC3D numerical simulation software was used to explore the weakening damage of thick hard rock body by different spacing of top-cutting holes. By comparing the stress evolution law and overburden transport under different schemes, the optimal top-cutting and pressure relief scheme parameters for different types of roofs are given.

Based on the actual geological conditions of 112203 working face, through the premise of roof classification, hydraulic fracture unloading as the center of the thick hard roof cutting and unloading technology. The field application results show that, compared with the non-fractured area, the cut top decompression technique reduces the surrounding rock stress by 50.02% on average, the displacement of top and bottom plate by 52.87% on average, and the displacement of both gangs by 46.36% on average, which effectively improves the stability of the coal column of the roadway and provides a theoretical reference for the control of thick and hard top plate in large mining face.

[1]谢和平, 苗鸿雁, 周宏伟. 我国矿业学科“十四五”发展战略研究[J]. 中国科学基金, 2021, 35(06): 856-863.

[2]许家林. 岩层控制与煤炭科学开采—记钱鸣高院士的学术思想和科研成就[J]. 采矿与安全工程学报, 2019, 36(01): 1-6.

[3]谢和平, 王金华, 姜鹏飞, 等. 煤炭科学开采新理念与技术变革研究[J]. 中国工程科学, 2015, 17(09): 36-41.

[4]康红普, 张镇, 黄志增. 我国煤矿顶板灾害特点及防控技术[J]. 煤矿安全, 2020, 51(10): 24-33+38.

[5]Jin Zhiyuan, Xu Youlin, Peng Tao, et al. Roof Control Technology of Mining Roadway under the Influence of Advanced Supporting Pressure[J]. Advance Civil Engineering, 2021.

[6]Kang Hongpu, Lv Huawen, Gao Fuqiang, et al. Understanding mechanisms of destressing mining-induced stresses using hydraulic fracturing[J]. International Journal of Coal Geology,2018, 196: 19-28.

[7]邓广哲, 黄炳香, 王广地, 等. 圆孔孔壁裂缝水压扩张的压力参数理论分析[J]. 西安科技学院学报, 2003(04): 361-364.

[8]邓广哲, 王健航, 张旭东. 综采工作面硬岩夹矸层预裂破碎技术研究[J]. 煤炭工程, 2021, 53(10): 95-99.

[9]康红普, 姜鹏飞, 冯彦军,等.煤矿巷道围岩卸压技术及应用[J]. 煤炭科学技术, 2022,50(06): 1-15.

[10]康红普, 冯彦军, 张震, 等. 煤矿井下定向钻孔水力压裂岩层控制技术及应用[J]. 煤炭科学技术, 2023, 51(01): 31-44.

[11]吴拥政, 付玉凯, 何杰, 等. 深部冲击地压巷道“卸压-支护-防护”协同防控原理与技术[J]. 煤炭学报, 2021, 46(01): 132-144.

[12]卢义玉, 黄杉, 葛兆龙, 等. 我国煤矿水射流卸压增透技术进展与战略思考[J]. 煤炭学报, 2022, 47(09): 3189-3211.

[13]黄炳香, 张农, 靖洪文, 等. 深井采动巷道围岩流变和结构失稳大变形理论[J]. 煤炭学报, 2020, 45(03): 911-926.

[14]陈树亮, 黄炳香. 井工矿坚硬顶煤顶板控制方法的技术经济分析[J].中国矿业, 2021,30(05): 130-135.

[15]孙可明, 张树翠. 水力压裂诱发断层活化机理分析[J]. 自然灾害学报, 2018, 27(01): 33-39.

[16]焦世雄. 高压水力压裂技术在坚硬顶板弱化控制中的应用[J]. 山东煤炭科技, 2023, 41(01): 55-57.

[17]Yang Chen, Zhou Fujian, Feng Wei, et al. Plugging mechan-ism of fibers and particulates in hydraulic fracture[J]. Journal of Petroleum Science and Engineering, 2019, 176: 396−402.

[18]翟振宇. 斜沟煤矿迎采掘巷水力压裂切顶卸压技术研究[J]. 煤矿现代化, 2022, 31(2): 98-100.

[19]边相君. 水力压裂切顶钻孔布置参数研究[J]. 陕西煤炭, 2021, 40(03): 131-134+169.

[20]许昭勇, 宋大钊, 邱黎明, 等. 煤层水力压裂过程“三场”演化规律特征[J]. 工矿自动化, 2016, 42(03): 39-43.

[21]于洋. 特厚煤层坚硬顶板破断动载特征及巷道围岩控制研究[D]. 中国矿业大学, 2015.

[22]Pan C, Zuo Y J, Gao S, et al. Numerical simulation on hard and stable roof control by means of directional hydraulic fracturing in coal mine[J]. Trans Tech Publications Ltd, 2014, 638: 894-897.

[23]Pan C, Xia B, Zuo Y, et al. Mechanism and control technology of strong ground pressure behaviour induced by high-position hard roofs in extra-thick coal seam mining[J]. International Journal of Mining Science and Technology, 2022, 32(3): 499-511.

[24]张庆国. 厚煤层综放工作面沿空掘巷坚硬顶板水力压裂弱化技术研究[J]. 中国煤炭, 2021, 47(12): 32-37.

[25]Gale G E. The effects of fractwe type (induced versus natural) on the stress fracture closure permeability relationships[J]. In: Proc, 23th Symp, On Rock Mech, Berkeley, California, 1982.

[26]Yu shi Z, Shicheng Z, Tong Z, et al. Experimental investigation into hydraulic fracture network propagation in gas shales using CT scanning technology[J]. Rock Mechanics & Rock Engineering, 2016, 49(1): 33-45.

[27]邓广哲, 郑锐, 徐东. 大采高综采端头悬顶水力切顶控制机理[J]. 西安科技大学学报, 2019, 39(02): 224-233.

[28]何满潮, 王亚军, 杨军, 等. 切顶成巷工作面矿压分区特征及其影响因素分析[J]. 中国矿业大学学报, 2018, 47(06): 1157-1165.

[29]何满潮, 高玉兵, 盖秋凯, 等. 无煤柱自动成巷力学原理及其工法[J]. 煤炭科学技术,2023, 51(01): 19-30.

[30]郭海豹, 王渊. 大采高切顶卸压小煤柱护巷围岩控制技术研究[J]. 煤炭技术, 2022, 41(12): 46-50.

[31]张晨, 白云龙, 张昌锁. 古城矿沿空留巷切顶卸压关键技术研究[J]. 煤炭技术, 2022, 41(11): 60-65.

[32]李仕牧, 杨皓博. 煤层压裂卸压防冲机制研究[J]. 煤炭技术, 2022, 41(08): 166-169.

[33]蔡燕伟. 水力切顶技术在大采高孤岛面的研究与应用[J]. 煤炭技术, 2021, 40(09):29-32.

[34]吴建星. 水力压裂卸压技术在双U工作面留巷围岩控制中的应用[J]. 煤矿安全, 2021, 52(05): 112-119.

[35]林健, 郭凯, 孙志勇, 等. 强烈动压巷道水力压裂切顶卸压压裂时机研究[J]. 煤炭学报, 2021, 46(S1): 140-148.

[36]付鑫, 尹煜鹏, 高振博, 等. 水力压裂护巷煤柱卸压机理与工程应用[J]. 煤炭技术, 2021, 40(02): 18-20.

[37]Zhang Q, He M, Wang J, et al. Investigation of a non-explosive directional roof cutting technology for self-formed roadway[J]. International Journal of Mining Science and Technology, 2022, 32(5): 997-1008.

[38]Liu Jiangwei, Liu Changyou, Yao Qiangling, etc. The position of hydraulic fracturing to initiate vertical fractures in hard hanging roof for stress relief[J]. International Journal of Rock Mechanics and Mining Sciences, 2020, 132: 104328.

[39]Kuang T, Li Z, Zhu W, et al. The impact of key strata movement on ground pressure behaviour in the Datong coalfield[J]. International Journal of Rock Mechanics and Mining Sciences, 2019, 119: 193-204.

[40]孙志勇, 张镇, 王子越, 等. 水力压裂切顶卸压技术在大采高留巷中的应用研究[J]. 煤炭科学技术, 2019, 47(10): 190-197.

[41]崔聪, 张浪. 水力压裂对煤层应力影响的实验研究[J]. 矿业安全与环保, 2018, 45(4):12-16+21.

[42]张明杰, 李永生. 煤层多点控制水力压裂机理及应用研究[J]. 煤炭技术, 2017, 36(1):143-144.

[43]李全贵, 翟成, 林柏泉, 等. 定向水力压裂技术研究与应用[J]. 西安科技大学学报, 2011, 31(06): 735-739.

[44]王高伟. 小保当矿强动压巷道切顶卸压-强帮护顶协同控制技术研究[J]. 煤炭技术, 2021, 40(09): 55-59.

[45]郭金刚, 李耀晖, 石松豪, 等. 厚硬基本顶切顶卸压成巷及围岩控制技术[J]. 煤炭学报, 2021, 46(09): 2853-2864.

[46]Gao R, Yang J, Kuang T, et al. Investigation on the Ground Pressure Induced by Hard Roof Fracturing at Different Layers during Extra Thick Coal Seam Mining[J].GEOFLUIDS, 2020,2020(8834235).

[47]Fu B, Tu M, Zhao Q. Pressure Control Technology at the Hard Thick Sandstone Roof in an Island Mining Face with a Large Mining Height[J]. TEHNICKI VJESNIK-TECHNICAL GAZETTE, 2020,27(6):1863-1869.

[48]折海成, 刘思其, 胡再强. 基于SEM数字图像的岩石结构特征分析方法[J]. 水电能源科学, 2022, 40(11): 167-170+175.

[49]赵善坤, 齐庆新, 李云鹏, 等. 煤矿深部开采冲击地压应力控制技术理论与实践[J].煤炭学报, 2020, 45(S2): 626-636.

[50]Haimson B, Fairhurst C. Initiation and extension of hydraulic fractures in rocks[J]. SPE Journal, 1967, 7(3): 310-318.

[51]王家臣, 许家林, 杨胜利, 等. 煤矿采场岩层运动与控制研究进展——纪念钱鸣高院士“砌体梁”理论40年[J]. 煤炭科学技术, 2023, 51(01): 80-94.

[52]Detournay E M, Cheng Alex. Influence of pressurization rate on the magnitude of the breakdown pressure[C]. In Rock Mechanics Proceedings of the 33rd U.S. Symposium, Publ by A A Balkema, 1992: 325-333.

[53]钱鸣高, 缪协兴, 许家林. 岩层控制中的关键层理论研究[J]. 煤炭学报, 1996(3): 2-7.

[54]MT/T554-1996, 缓倾斜煤层采煤工作面顶板分类[S].

[55]黄庆享, 李康华, 曹健. 浅埋近距离采空区下工作面矿压特征与顶板结构分析[J]. 陕西煤炭, 2021, 40(01): 12-17.

[56]Zhang Wei, Zhang Yandong, Zhang Weisheng,et al. Roof-Breaking Characteristics and Ground Pressure Behavior in Deep Jurassic Coal Seams: A Thick-Plate Model and Field Measurements[J]. Geofluids, 2022, 2022.

[57]王家臣, 王兆会, 唐岳松, 等. 千米深井超长工作面顶板分区破断驱动机制与围岩区域化控制研究[J]. 煤炭学报: 1-11[2023-04-05].

[58]J.W. Liu, C.Y. Liu, X.H. Li. Determination of fracture location of double-sided directionalfracturing pressure relief for hard roof of large upper goaf-side coal pillars[J]. Energy Exploration & Exploitation, 2020, 38(1): 111−136

[59]M M Rahman, M M Hossain, D G. Crosby. Analytical numerical and experimental investigations of transverse fracture propagation from horizontal wells[J]. Journal of Petroleum Science and Engineering. 2002(35): 127-15.

[60]Dezhong Kong,Yahui Lou,Shangshang Zheng,Shijiang Pu. The Characteristics of Roof Breaking and the Law of Ground Pressure Behavior in Fully Mechanized Top-coal Caving Face with Large Mining Height[J]. Geotechnical and Geological Engineering,2020,39.

[61]钱鸣高, 缪协兴, 何富连. 采场“砌体梁”结构的关键块分析[J]. 煤炭学报, 1994(06):557-563.

[62]黄庆享, 李锋, 贺雁鹏, 等. 浅埋大采高工作面超前支承压力峰值演化规律[J]. 西安科技大学学报, 2021, 41(01): 1-7.

[63]刘长友, 刘江伟. 煤岩体裂化的弱结构体应力转移原理及应用[J]. 采矿与安全工程学报, 2022, 39(02): 359-369.

[64]徐芝纶. 弹性力学简明教程[M]. 北京, 高等教育出版社, 2018.

[65]Physics; New Findings on Physics from Northeast Electric Power University Summarized (On random elastic constraint conditions of Levinson beam model considering the violation of Saint-Venant's principle in dynamic)[J]. Journal of Technology & Science,2020.

[66]何满潮, 高玉兵, 盖秋凯, 等. 无煤柱自成巷力学原理及其工法[J]. 煤炭科学技术, 2023, 51(01): 19-30.

[67]康红普, 姜鹏飞, 黄炳香, 等. 煤矿千米深井巷道围岩支护-改性-卸压协同控制技术[J]. 煤炭学报, 2020, 45(03): 845-864.

[68]何春光, 徐晓鼎, 杨建辉, 等. 厚硬顶板切顶卸压围岩变形控制技术研究[J]. 煤炭工程, 2022, 54(09): 59-63.

[69]邓广哲, 郑锐, 徐东. 大采高综采端头悬顶水力切顶控制机理[J]. 西安科技大学学报, 2019, 39(02): 224-233.

[70]朱治刚, 李迎富, 陈涛, 等. 坚硬厚层顶板破断规律与围岩控制研究[J]. 煤炭技术: 1-16[2023-04-05].

[71]高明仕, 徐东, 贺永亮, 等. 厚硬顶板覆岩冲击矿震影响的远近场效应研究[J]. 采矿与安全工程学报, 2022,39(02): 215-226.

[72]王有熙, 邓广哲. 煤层注水破坏机理的能量耗散分析[J]. 西安科技大学学报, 2013, 33(02):143-148.

[73]赵延林, 刘强, 刘欢, 等. 水-力耦合作用下单裂隙灰岩三轴压缩与声发射试验及压剪断裂模型[J]. 煤炭学报, 2021, 46(12): 3855-3868.