我国煤炭资源丰富，多数煤田含有多层可采或局部可采煤层。煤层群开采后覆岩裂隙演化、卸压瓦斯储运区形态特征以及瓦斯抽采系统布置与单一煤层开采相比更加复杂，仍是我国矿井瓦斯治理的重要方向之一。本文从理论、物理相似模拟实验及数值模拟分析了开采煤层群条件下覆岩裂隙演化规律，明确了卸压瓦斯储运区形成演化特征，并将研究结果应用到矿井现场。

论文运用物理相似模拟实验和FLAC^3D数值模拟，分析了煤层群开采后覆岩裂隙演化规律和应力变化特征。得到单一上煤层回采后初次来压步距40m，平均周期来压步距18.3m，垮落带高度12m，裂隙带高度58m；煤层群重复采动后初次来压步距37m，平均周期来压步距14.1m，垮落带高度14m，裂隙带高度85.5m。单一煤层采动后边界煤柱和工作面前方应力集中，采空区中部卸压并随着上覆岩层下沉压实应力逐渐恢复；煤层群双重卸压开采导致采空区上、下方煤岩体应力进一步降低，采空区四周煤岩体应力进一步升高。

分析得到煤层群重复采动后卸压瓦斯储运区形态及特征参数变化，认为单一煤层回采后沿煤层走向和倾向剖面是梯形状，纵向剖面为“O”形裂隙圈；煤层群重复采动后梯形状裂隙区相互叠加，纵向剖面“O”形裂隙圈覆岩下沉量增大。煤层群回采后裂隙网络发育完善，储运区垮落角、宽度大于单一煤层开采；煤层群开采后卸压瓦斯储运区离层率增大，是单一煤层开采的1.3倍；卸压瓦斯储运区内破断裂隙发育充分，贯通度增大，卸压瓦斯向上部升浮运移能力增强。

基于现场工作面实际回采情况，确定卸压瓦斯抽采方式。通过分别监测煤层群上下两煤层工作面瓦斯抽采情况，分析工作面瓦斯抽采效果，进一步验证论文研究结果及抽采系统布置优化的合理性，保证了工作面安全开采，为同类开采煤层群矿井卸压瓦斯抽采提供了参考借鉴，对于实现瓦斯精准抽采具有重要意义。

China is rich in coal resources, and most coal fields contain multiple recoverable or partially recoverable coal seams. The overburden fracture evolution, morphological characteristics of unloading gas storage and transportation area and gas extraction system arrangement are more complicated after mining coal seam clusters compared with single seam mining, which is still one of the important directions of gas management in China's mines. In this paper, we analyze the evolution of overburden fissures under mining coal seam group conditions from theoretical, physically similar simulation experiments and numerical simulations, and clarify the formation and evolution characteristics of unloading gas storage and transportation zones, and apply the research results to mine sites.

The paper analyzes the overburden fracture evolution law and stress change characteristics after mining the coal seam group by using physical similar simulation experiments and FLAC3D numerical simulation. The initial incoming pressure step is 40m, the average cycle incoming pressure step is 18.3m, the collapse zone height is 12m, and the fissure zone height is 58m after single upper seam mining; the initial incoming pressure step is 37m, the average cycle incoming pressure step is 14.1m, the collapse zone height is 14m, and the fissure zone height is 85.5m after repeated mining of the coal seam group. The stresses in the central part of the mining area are decompressed and gradually recovered with the overburden compaction stresses; the double decompression mining of the coal seam group leads to further reduction of the stresses in the coal and rock bodies above and below the mining area and further increase of the stresses in the coal and rock bodies around the mining area.

After repeated mining of the coal seam group, the shape and characteristic parameters of the unloading gas storage and transportation area change, and it is considered that the single coal seam is trapezoidal along the coal seam direction or tendency profile after back mining, and the longitudinal profile is "O" fissure circle; after repeated mining of the coal seam group, the trapezoidal fissure area is superimposed on each other, and the longitudinal profile is "O" fissure circle. O"-shaped fissure circle in the longitudinal section increases the amount of overburden sinking. The fracture network is well developed after coal seam group mining, and the collapse angle and width of storage and transportation area are larger than those of single seam mining; the rate of unloading gas storage and transportation area after coal seam group mining is 1.3 times of that of single seam mining; the broken fractures are well developed after coal seam group mining, and the penetration degree increases, so the ability of unloading gas to float upward is enhanced, and the gas extraction system can be arranged to higher levels to get better extraction effect.

Based on the actual recovery situation of the working face, the unloading gas extraction method is determined. By monitoring the gas extraction situation in the working face of the upper and lower coal seam group separately and analyzing the effect of three-dimensional gas extraction in the working face, the results of the thesis and the rationality of the optimized extraction system arrangement are further verified, which ensure the safe mining of the working face and provide a reference for the unloading gas extraction in similar mines of the coal seam group and are of great significance for the realization of accurate gas extraction.

[1] 钱鸣高,许家林. 煤炭开采与岩层运动[J]. 煤炭学报, 2019, 44(4): 973-984.

[2] 高小康,马军,路艳霞,等. 贵州西部织金区块多煤层条件下煤层气开发序列[J]. 天然气工业, 2018, 38(S1): 31-37.

[3] 袁亮. 我国深部煤与瓦斯共采战略思考[J]. 煤炭学报, 2016, 41(1): 1-6.

[4] 秦宗浩,杨兆彪,秦勇,等. 贵州西部地区煤层气井产出气地球化学特征[J]. 煤炭学报, 2020, 45(2): 712-720.

[5] 钱鸣高,许家林,王家臣. 再论煤炭的科学开采[J]. 煤炭学报, 2018, 43(1): 1-13.

[6] 袁亮,张平松. 煤炭精准开采透明地质条件的重构与思考[J]. 煤炭学报, 2020, 45(7): 2346-2356.

[7] 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(1): 1-6.

[8] 何祥,杨科,袁亮,等.双关键层跨煤组远程卸压增透效应试验研究[J]. 中国矿业大学学报, 2020, 49(2): 238-246.

[9] 黄庆享,韩金博. 浅埋近距离煤层开采裂隙演化机理研究[J]. 采矿与安全工程学报, 2019, 36(4): 706-711.

[10] 卢国志,汤建泉,宋振骐. 传递岩梁周期裂断步距与周期来压步距差异分析[J]. 岩土工程学报, 2010, 32(4): 538-541.

[11] 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,(03): 2-7.

[12] Bai-m,Elsworth-D.Some aspects of mining under aquifers in China[J].Mining Science and Technology,1990,10(1):81-91.

[13] J Kim.Fully coupled poroelastic governing equations for groundwater flow and soldskeleton deformation in variably saturated true anisotropic porous geologic media[J].Geosciences Journal,2004,8(3):291-294.

[14] Karmis-m,Triplett-T,Haycocks-C.Mining subsidence and its prediction in the appalachian coal field[J]. Rock Mechanics:theory,experiment,practice.1983,7(11):665-675.

[15] 钱鸣高，石平五.矿山压力与岩层控制[M].徐州:中国矿业大学出版社，2003:89-94.

[16] 宋振骐.实用矿山压力控制[M].徐州:中国矿业大学出版社，1988:57-62.

[17] Hasenfus GJ,Johnson KL.A hydrogen mechanical study of overburden aquifer response to longwall mining[C].Proceedings,7th Conf.Ground Crotrol in Mining.Morgantown:West Virginia University,1988:149-162.

[18] Palchik V.Influence of physical characteristics of weak rock mass on height of caved zone over abandoned subrface coal mines[J].Environmental Geology,2002,42(1):92-101.

[19] 钱鸣高,茅献彪,缪协兴. 采场覆岩中关键层上载荷的变化规律[J]. 煤炭学报, 1998,(2): 3-5.

[20] 钱鸣高,许家林. 覆岩采动裂隙分布的“O”形圈特征研究[J]. 煤炭学报, 1998,(5): 3-5.

[21] 谢和平,陈忠辉,王家臣. 放顶煤开采巷道裂隙的分形研究[J]. 煤炭学报, 1998,(3): 3-5.

[22] 缪协兴,茅献彪,钱鸣高. 采动覆岩中关键层的复合效应分析[J]. 矿山压力与顶板管理, 1999, (Z1):3-5.

[23] 李树刚,石平五,钱鸣高. 覆岩采动裂隙椭抛带动态分布特征研究[J]. 矿山压力与顶板管理, 1999, (Z1): 3-5.

[24] 许家林,钱鸣高. 岩层采动裂隙分布在绿色开采中的应用[J]. 中国矿业大学学报, 2004,(2):17-20+25.

[25] 李树刚. 综放开采围岩活动影响下瓦斯运移规律及其控制[J]. 岩石力学与工程学报, 2000,(6):809-810.

[26] 李树刚,林海飞,赵鹏翔,等. 采动裂隙椭抛带动态演化及煤与甲烷共采[J]. 煤炭学报, 2014, 39(8): 1455-1462.

[27] 涂敏. 潘谢矿区采动岩体裂隙发育高度的研究[J]. 煤炭学报, 2004,(06):641-645.

[28] 黄炳香,刘长友,许家林. 采动覆岩破断裂隙的贯通度研究[J]. 中国矿业大学学报, 2010,39(1):45-49.

[29] 杨科,谢广祥. 深部长壁开采采动应力壳演化模型构建与分析[J]. 煤炭学报, 2010,35(7):1066-1071.

[30] 程久龙. 矿山采动裂隙岩体地球物理场特征研究及工程应用[J]. 中国矿业大学学报, 2008,(6):877-879.

[31] 宋颜金,程国强,郭惟嘉. 采动覆岩裂隙分布及其空隙率特征[J]. 岩土力学, 2011,32(2):533-536.

[32] 肖鹏,李树刚,林海飞,等. 基于物理相似模拟实验的覆岩采动裂隙演化规律研究[J]. 中国安全生产科学技术, 2014,10(4):18-23.

[33] 袁亮,郭华,沈宝堂,等. 低透气性煤层群煤与瓦斯共采中的高位环形裂隙体[J]. 煤炭学报, 2011, 36(3): 357-365.

[34] 袁亮. 低透气煤层群首采关键层卸压开采采空侧瓦斯分布特征与抽采技术[J]. 煤炭学报, 2008, 33(12): 1362-1367.

[35] 袁亮. 低透高瓦斯煤层群安全开采关键技术研究[J]. 岩石力学与工程学报, 2008,(7): 1370-1379.

[36] 卢平,袁亮,程桦,等. 低透气性煤层群高瓦斯采煤工作面强化抽采卸压瓦斯机理及试验[J]. 煤炭学报, 2010, 35(4): 580-585.

[37] 夏红春,程远平,柳继平. 利用覆岩移动特性实现煤与瓦斯安全高效共采[J]. 辽宁工程技术大学学报, 2006,(2): 168-171.

[38] 程远平,俞启香. 煤层群煤与瓦斯安全高效共采体系及应用[J]. 中国矿业大学学报, 2003,(05): 5-9.

[39] 杨国枢,王建树. 近距离煤层群二次采动覆岩结构演化与矿压规律[J]. 煤炭学报, 2018, 43(S2): 353-358.

[40] 李树刚,丁洋,安朝峰,等. 近距离煤层重复采动覆岩裂隙形态及其演化规律实验研究[J]. 采矿与安全工程学报, 2016, 33(5): 904-910.

[41] 李树清,何学秋,李绍泉,等. 煤层群双重卸压开采覆岩移动及裂隙动态演化的实验研究[J]. 煤炭学报, 2013, 38(12): 2146-2152.

[42] 张勋,邓存宝,王继仁,等.纵深大区域煤层群开采覆岩活动规律相似模拟[J].中国安全生产科学技术,2015,11(06):5-11.

[43] 王志强,高健勋,武超,等.近距离煤层上行开采巷道优化布置及煤层卸压效果试验分析[J].中国安全生产科学技术,2020,16(03):61-67.

[44] 马海峰,王文龙,李传明,等. 叠加开采裂隙场演化与优势瓦斯通道形成机制[J]. 中国安全科学学报, 2017, 27(6): 133-138.

[45] Liu T,Lin B,Xiao W, et al. A Safe Mining Approach for Deep Outburst Coal Seam Groups with Hard‐thick Sandstone Roof: Stepwise Risk Control Based on Gas Diversion and Extraction[J]. Energy Science & Engineering, 2020, 8(8).

[46] Yuan B,Benqing Y. Study on the Co-mining Mode of Coal and Gas in Protective Layer of Coal Seam Group[J]. Iop Conference Series: Earth and Environmental Science, 2020, 558(2):022081.

[47] 程志恒,齐庆新,李宏艳,等. 近距离煤层群叠加开采采动应力-裂隙动态演化特征实验研究[J]. 煤炭学报, 2016, 41(2): 367-375.

[48] 张勇,刘传安,张西斌,等. 煤层群上行开采对上覆煤层运移的影响[J]. 煤炭学报, 2011, 36(12): 1990-1995.

[49] 薛俊华. 近距离高瓦斯煤层群大采高首采层煤与瓦斯共采[J]. 煤炭学报, 2012, 37(10): 1682-1687.

[50] 黄汉富,闫志刚,姚邦华,等. 万利矿区煤层群开采覆岩裂隙发育规律研究[J]. 采矿与安全工程学报, 2012, 29(5): 619-624.

[51] 吴仁伦. 关键层对煤层群开采瓦斯卸压运移“三带”范围的影响[J]. 煤炭学报, 2013, 38(6): 924-929.

[52] 孙力,杨科,闫书缘,等. 近距离煤层群下行开采覆岩运移特征试验分析[J]. 地下空间与工程学报, 2014, 10(5): 1158-1163.

[53] 窦礼同,杨科,闫书缘. 近距离煤层卸压开采围岩力学特征试验研究[J]. 地下空间与工程学报, 2014, 10(5): 1177-1182.

[54] 潘瑞凯,曹树刚,李勇,等. 浅埋近距离双厚煤层开采覆岩裂隙发育规律[J]. 煤炭学报, 2018, 43(8): 2261-2268.

[55] Ha SN,Karmakar S.Thick seam mining-some experience and exaltation.In:Singh TN,Dhar BB editors.[J]Proceedings of the international symposium on thick seam mining. India,Dhanbad:Central Mining Research Station,1992:191-202.

[56] Liu T,Lin B,Fu X, et al. Experimental Study on Gas Diffusion Dynamics in Fractured Coal: a Better Understanding of Gas Migration in In-situ Coal Seam[J]. Energy, 2020, 195:117005.

[57] N.E Yasitli.B.Unver,3D numerical modeling of longwall mining with top-coal caving.[J]International Joumal of Rock Mechanics & Mining Science,2005,219-235.

[58] Rutqvist J,Stephansson O.The role of hydromechanical coupling in fractured rock engineering[J].Hydrogeology Journal.2003,11(1):7-40

[59] Wang H,Li T,Zou Q, et al. Influences of Path Control Effects on Characteristics of Gas Migration in a Coal Reservoir[J]. Fuel, 2020, 267.

[60] Zhao W,Wang K,Cheng Y, et al. Evolution of Gas Transport Pattern with the Variation of Coal Particle Size: Kinetic Model and Experiments[J]. Powder Technology, 2020, 367:336-346.

[61] 肖康,穆龙新,姜汉桥. 基于网络模型的油藏优势通道形成微观机制[J]. 大庆石油地质与开发, 2017, 36(3): 64-69.

[62] 赵鹏翔,卓日升,李树刚,等. 综采工作面推进速度对瓦斯运移优势通道演化的影响[J]. 煤炭科学技术, 2018, 46(7): 99-108.

[63] Zhao PX,Zhuo RS,Li S,et al.Analysis of advancing speed effect in gas safety extraction channels and pressure-relief gas extraction[J].Fuel,2020,265:116825.

[64] Zhao PX,Zhuo RS,Li S,et al.Fractal characteristics of gas migration channels at differents mining heights[J].Fuel,2020,271:117479.

[65] Zhao PX,Zhuo RS,Li S,et al.Research on the effect of coal seam inclination on gas migration channels at fully mechanized coal mining face[J].Arabian Journal of Geosciences,2019,12(18):597.

[66] 张勇,张保,张春雷,等. 厚煤层采动裂隙发育演化规律及分布形态研究[J]. 中国矿业大学学报, 2013, 42(6): 935-940.

[67] 张勇,许力峰,刘珂铭,等. 采动煤岩体瓦斯通道形成机制及演化规律[J]. 煤炭学报, 2012, 37(9): 1444-1450.

[68] 李立. 采动影响下煤体瓦斯宏细观尺度通道演化机理研究[D]. 中国矿业大学(北京), 2016.

[69] 刘洪永,程远平,周红星,等. 综采长壁工作面推进速度对优势瓦斯通道的诱导与控制作用[J]. 煤炭学报, 2015, 40(4): 809-815.

[70] 齐庆新,彭永伟,汪有刚,等. 基于煤体采动裂隙场分区的瓦斯流动数值分析[J]. 煤矿开采, 2010, 15(5): 8-10.

[71] 吴仁伦,王亚飞,徐东亮,等. 工作面面宽对煤层群开采瓦斯卸压运移“三带”范围的影响[J]. 采矿与安全工程学报, 2017, 34(1): 192-198.

[72] Dirk Mallants,Rob Jeffrey,Xi Zhang,et al. Review of plausible chemical migration pathways in Australian coal seam gas basins[J].International Journal of Coal Geology, 2018,195(7): 280-303.

[73] Liang Wang,Yuan-ping Cheng, Feng-rong Li,et al. Fracture evolution and pressure relief gas drainage from distant protected coal seams under an extremely thick key stratum[J]. Journal of China University of Mining and Technology,2008,18(2):182-186.

[74] Zheng-dong Liu, Yuan-ping Cheng, Qing-quan Liu,et al. Numerical assessment of CMM drainage in the remote unloaded coal body: Insights of geostress-relief gas migration and coal permeability[J]. Journal of Natural Gas Science and Engineering.2017,45:487-501.

[75] 苏伟伟. 近距离下邻近煤层群开采采空区瓦斯治理技术[J]. 中国安全科学学报, 2018, 28(12): 83-88.

[76] 徐晓乾,孟应芳,段正鹏,等. 贵州省煤层气(瓦斯)开发适用性技术分析[J]. 煤田地质与勘探, 2019, 47(6): 8-13.

[77] 杨正凯,程志恒,刘彦青,等. 突出煤层群多次采动对底板穿层钻孔瓦斯抽采的影响[J]. 中国安全科学学报, 2020, 30(5): 66-73.

[78] 程远平,俞启香,袁亮. 上覆远程卸压岩体移动特性与瓦斯抽采技术[J]. 辽宁工程技术大学学报, 2003, (4): 483-486.

[79] 程详,赵光明,李英明,等. 软岩保护层开采覆岩采动裂隙带演化及卸压瓦斯抽采研究[J]. 采矿与安全工程学报, 2020, 37(3): 533-542.

[80] 甘林堂. 地面钻井抽采被保护层采动区卸压瓦斯技术研究[J]. 煤炭科学技术, 2019, 47(11): 110-115.

[81] 夏红春,程远平.覆岩移动特性的数值模拟及其在煤矿安全中的应用[J].西安科技大学学报,2005(4):420-424.

[82] 肖峻峰,樊世星,卢平,等. 近距离高瓦斯煤层群倾向高抽巷抽采卸压瓦斯布置优化[J]. 采矿与安全工程学报, 2016, 33(3): 564-570.

[83] 林海飞,杨二豪,夏保庆,等. 高瓦斯综采工作面定向钻孔代替尾巷抽采瓦斯技术[J]. 煤炭科学技术, 2020, 48(1): 136-143.

[84] 张坤,吴克平,柳蓉. 舒兰盆地水曲柳矿区煤层气富集因素分析[J]. 特种油气藏, 2017, 24(3): 44-48.

[85] 吴国代,曾春林,程军,等. 松藻矿区地下水动力场特征及其对煤层气富集的影响[J]. 煤田地质与勘探, 2018, 46(4): 55-60.

[86] 刘超,李树刚,薛俊华,等. 基于微震监测的采空区覆岩高位裂隙体识别方法[J]. 中国矿业大学学报, 2016, 45(4): 709-716.

[87] 陈贞龙,汤达祯,许浩,等. 黔西滇东地区煤层气储层孔隙系统与可采性[J]. 煤炭学报, 2010, 35(S1): 158-163.

[88] 刘永茜. 构造控制下的平煤十三矿煤层气运移规律[J]. 煤炭科学技术, 2016, 44(11): 93-97.

[89] 赵继展,张群,张培河. 煤矿采动条件下煤层气储层模型及应用[J]. 煤田地质与勘探, 2017, 45(6): 34-39.

[90] 石迎爽,梁冰,薛璐,等. 煤层气多层合采井生产特征分析[J]. 天然气地球科学, 2020, 31(8): 1161-1167.

[91] 龚选平,武建军,李树刚,等. 低瓦斯煤层高强开采覆岩卸压瓦斯抽采合理布置研究[J]. 采矿与安全工程学报, 2020, 37(2): 419-428.

[92] 林海飞,李树刚,成连华,等.覆岩采动裂隙带动态演化模型的实验分析[J].采矿与安全工程学报,2011,28(2):298-303.

[93] 林海飞,李树刚,索亮,等.走向高抽巷合理层位的FLUENT数值模拟[J].辽宁工程技术大学学报,2014,33(02):172-176.

[94] 袁亮.留巷钻孔法煤与瓦斯共采技术[J].煤炭学报,2008(8):898-902.

[95] 于宝种.上隅角不同插管深度瓦斯抽采效果研究[J].煤矿安全,2017,48(7):169-172.

[96] 李树刚,李生彩,林海飞,等.卸压瓦斯抽取及煤与瓦斯共采技术研究[J].西安科技学院学报,2002(3):247-249+263.

[97] 秦跃平,姚有利,刘长久.铁法矿区地面钻孔抽放采空区瓦斯技术及应用[J].辽宁工程技术大学学报,2008(1):5-8.

[98] 赵建国.煤层顶板高位定向钻孔施工技术与发展趋势[J].煤炭科学技术,2017,45(6):137-141+195.

[99] 许超,刘飞,方俊.高位定向长钻孔瓦斯抽采技术及抽采效果分析[J].煤炭工程,2017,49(6):8－81．

[100] 于辉.近距离煤层开采覆岩结构运动及矿压显现规律研究[D].中国矿业大学(北京),2015.

[101] Wu H, Zhou YF, Yao YB, Wu KJ. Imaged based fractal characterization of micro-fracture structure in coal. Fuel 2019;239:53-62.

[102] 林海飞,李树刚,赵鹏翔,等.我国煤矿覆岩采动裂隙带卸压瓦斯抽采技术研究进展[J].煤炭科学技术,2018,46(01):28-35.

[103] 高宏,杨宏伟.高瓦斯矿井高、底抽巷联合抽采瓦斯技术研究[J].工矿自动化,2021,47(1):100-106.