浅埋近距离煤层开采裂隙演化机理研究
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摘要
为研究浅埋近距离煤层群下行开采下煤层采场上覆岩层裂隙二次扩展机理,本文以柠条塔煤矿浅埋近距离煤层群开采为工程背景,通过FLAC3D数值计算、物理相似模拟及理论分析,得出煤层群下煤层采场上覆岩层裂隙二次扩展的基本特征和应力场分布,覆岩裂隙以张剪型复合裂隙为主,裂隙尖端起裂符合最大正应力准则。基于宏观裂隙与微观裂隙的相似性原理,建立裂隙扩展力学模型,应用裂隙尖端断裂能量理论和Griffith准则,给出了裂隙扩展方向、起裂应力强度因子、扩展速度和裂隙发育高度计算公式。
In order to investigate the mechanism of secondary fracture propagation in overburden of lower coalface during shallow-buried close coal seam mining, the mining practice of shallow close coal seams in Ningtiaota coalmine is taken as the example in this study. Through FLAC3 D calculation, physical simulation and theoretical analysis, the secondary fracture propagation feature and stress field in the overburden of lower coalface were obtained. The overburden fractures are mainly tensile-shear composite fractures, and fracture initiation follows the maximum normal stress criterion. Based on the similarity between macro fracture and micro fracture, the mechanical model of fracture propagation was established. The formulas of fracture propagation direction, initiation stress intensity factor, fracture propagation velocity and fracture height were developed by adopting the energy theory of fracture tip and Griffith criterion.
In order to investigate the mechanism of secondary fracture propagation in overburden of lower coalface during shallow-buried close coal seam mining, the mining practice of shallow close coal seams in Ningtiaota coalmine is taken as the example in this study. Through FLAC3 D calculation, physical simulation and theoretical analysis, the secondary fracture propagation feature and stress field in the overburden of lower coalface were obtained. The overburden fractures are mainly tensile-shear composite fractures, and fracture initiation follows the maximum normal stress criterion. Based on the similarity between macro fracture and micro fracture, the mechanical model of fracture propagation was established. The formulas of fracture propagation direction, initiation stress intensity factor, fracture propagation velocity and fracture height were developed by adopting the energy theory of fracture tip and Griffith criterion.
引文
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[11]刘伟韬,申建军.含单裂纹真实岩石试件断裂模式的力学试验研究[J].岩石力学与工程学报,2016,35(6):1182-1190.LIU Weitao,SHEN Jianjun.Mechanical test of fracture mode of real rock specimens containing single crack[J].Journal of Rock Mechanics and Engineering,2016,35(6):1182-1190.
[12]诺特J,威西P.断裂力学应用实例[M].北京:科学出版社,1995:123-124.
[13]FERUND L B.Dynamic fracture mechanics.Edin[M].Burgh:Cambridge University Press,1990:165-166.
[2]樊永山,张胜云.近距离煤层群下行开采下煤层覆岩运移规律模拟[J].辽宁工程技术大学学报:自然科学版,2015,34(8):887-891.FAN Yongshan,ZHANG Shengyun.Study on analogue simulation for overlying strata movement rule of lower layer in mining the close coal seams[J].Journal of Liaoning Technical University:Natural Science,2015,34(8):887-891.
[3]邢宇祺,宁建国,徐国栋,等.浅埋不同间距煤层群开采对地表沉陷的影响[J].现代矿业,2015(5):20-22.XING Yuqi,NING Jianguo,XU Guodong,et al.The effects of shallow-buried coal seam mining on surface subsidence[J].Modern Mining,2015(5):20-22.
[4]胡永忠,刘长郄,刘长友,等.煤层群混合开采采动裂隙发育规律研究[J].采矿与安全工程学报,2015,32(3):396-400.HU Yongzhong,LIU Changxi,LIU Changyou,et al.Research on mining fracture development law of mixed mining in coal seam group[J].Journal of Mining and Safety Engineering,2015,32(3):396-400.
[5]余明高,滕飞,褚廷湘,等.浅埋煤层重复采动覆岩裂隙及漏风通道演化模拟研究[J].河南理工大学学报(自然科学版),2018,37(1):001-007.YU Minggao,TENG Fei,CHU Tingxiang,et al.Simulation Study on the evolution of the overlying strata fracture development and air-leaking passage under repeated coal-mining of shallow coal seams[J].Journal of Henan Polytechnic University(Natural Science),2018,37(1):001-007.
[6]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.HUANG Hanfu,YAN Zhigang,YAO Banghua,et al.Study on the law of development of overburden cracks in shallow-buried coal seam group of Wanli mining area[J].Journal of Mining and Safety Engineering,2012,29(5):619-624.
[7]刘洪涛,赵志强,张胜凯,等.近距离煤层群围岩碎裂特征与裂隙分布关系[J].煤炭学报,2015,40(4):766-773.LIU Hongtao,ZHAO Zhiqiang,ZHANG Shengkai,et al.Relationship between failure characteristics and fracture spacing of surrounding rock of short-distance coal seams group[J].Journal of China Coal Society,2015,40(4):766-773.
[8]杨艳国,吴庆伟,石亚军.某煤矿导水裂隙带发育高度计算[J].科技导报,2014,32(3):34-38.YANG Yanguo,WU Qingwei,SHI Yajun.Calculation on the height of water flowing fractured zone in a coal mine[J].Science and Technology Review,2014,32(3):34-38.
[9]李银平,杨春和.裂纹几何特征对压剪复合断裂的影响分析[J].岩石力学与工程学报,2006,25(3):462-466.LI Yinping,YANG Chunhe.Influence of geometric characteristics of cracks on composite fractures under compression-shear loading[J].Chinese Journal of Rock Mechanics and Engineering,,2006,25(3):462-466.
[10]王自强,陈少华.高等断裂力学[M].北京:科学出版社,2006:56-57.
[11]刘伟韬,申建军.含单裂纹真实岩石试件断裂模式的力学试验研究[J].岩石力学与工程学报,2016,35(6):1182-1190.LIU Weitao,SHEN Jianjun.Mechanical test of fracture mode of real rock specimens containing single crack[J].Journal of Rock Mechanics and Engineering,2016,35(6):1182-1190.
[12]诺特J,威西P.断裂力学应用实例[M].北京:科学出版社,1995:123-124.
[13]FERUND L B.Dynamic fracture mechanics.Edin[M].Burgh:Cambridge University Press,1990:165-166.