深井超长工作面基本顶分区破断模型与支架阻力分布特征
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摘要
开采深度和工作面长度增加导致采场矿压显现程度和空间分布特征发生改变,增加了该类采场围岩失稳类型的不确定性及控制难度。针对深井超长工作面异常矿压现象发生频率高、预测难度大等问题,采用理论分析、室内实验和实测等方法分析了该类采场基本顶破断类型和支架阻力分布特征。结果表明:开采深度增加提高了岩体中裂隙发育程度,裂隙尺寸服从对数正态分布,裂隙倾角和倾向服从正态分布;基于蒙特-卡罗模拟方法实现深井超长工作面基本顶三维重构,工作面长度增加导致基本顶中部存在裂隙的概率升高,增大了基本顶在工作面中部发生局部破断的可能性;建立深井超长工作面基本顶分区破断力学模型,采用上限定理推导出完整基本顶的整体承载能力以及基本顶中存在1条和2条原生裂隙时的局部承载能力,获得基本顶在裂隙影响区发生局部分区破断和迁移现象的力学判据;基本顶分区破断现象导致破断岩块在空间上呈非均匀分布,表现为工作面中部块度小、两端块度大的特征;分区破断模型预测结果同相似模拟实验结果吻合,解释了深井超长工作面开采实践中发现的顶板压力沿工作面方向的非均匀分布现象。
The increase in the cover depth and length of longwall face leads to some drastic changes in mine pressure occurrence and spatial distribution.Such changes result in a great challenge in surrounding rock control.In order to realize an effective control of the abnormal mine pressure occurrences,happening frequently and difficult to be predicted in deep longwall face with ultra-large length,the roof rupture characteristics and support resistance distribution in such a longwall face are investigated.Pre-existing fracture development significantly increases due to the increase of cover depth.The fracture size and orientations obey lognormal and normal distributions,respectively.The main roof with randomly distributed fractures is reconstructed based on such statistical distributions and DFN method.The large length of longwall face increases the probability of the existence of fractures in exposed main roof.Sub-regional rupture model isestablished for the main roof with one and two fractures,whose limit load-bearing capacities are achieved.The mechanical condition for the occurrence of the sub-regional rupture of main roof and its subsequent migration is achieved using upper bound theory.Spatial distribution of the broken blocks after the main roof fracturing is non-uniform. The block volume in the middle section of the longwall face is small while that of the blocks on two sides of the longwall face is relatively large.Such distribution reasonably explains the non-uniform distribution of the support resistance along the dip direction of the longwall face.The theoretical conclusions are in good accordance with the experimental results and field measurement.
The increase in the cover depth and length of longwall face leads to some drastic changes in mine pressure occurrence and spatial distribution.Such changes result in a great challenge in surrounding rock control.In order to realize an effective control of the abnormal mine pressure occurrences,happening frequently and difficult to be predicted in deep longwall face with ultra-large length,the roof rupture characteristics and support resistance distribution in such a longwall face are investigated.Pre-existing fracture development significantly increases due to the increase of cover depth.The fracture size and orientations obey lognormal and normal distributions,respectively.The main roof with randomly distributed fractures is reconstructed based on such statistical distributions and DFN method.The large length of longwall face increases the probability of the existence of fractures in exposed main roof.Sub-regional rupture model isestablished for the main roof with one and two fractures,whose limit load-bearing capacities are achieved.The mechanical condition for the occurrence of the sub-regional rupture of main roof and its subsequent migration is achieved using upper bound theory.Spatial distribution of the broken blocks after the main roof fracturing is non-uniform. The block volume in the middle section of the longwall face is small while that of the blocks on two sides of the longwall face is relatively large.Such distribution reasonably explains the non-uniform distribution of the support resistance along the dip direction of the longwall face.The theoretical conclusions are in good accordance with the experimental results and field measurement.
引文
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[2]谢和平,高峰,鞠杨,等.深部开采的定量界定与分析[J].煤炭学报,2015,40(1):1-10.XIE Heping,GAO Feng,JU Yang,et al. Quantitative definition and investigation of deep mining[J]. Journal of China Coal Society,2015,40(1):1-10.
[3]康红普,王国法,姜鹏飞,等.煤矿千米深井围岩控制及智能开采技术构想[J].煤炭学报,2018,43(7):1789-1800.KANG Hongpu,WANG Guofa,JIANG Pengfei,et al. Conception for strata control and intelligent mining technology in deep coal mines with depth more than 1000m[J]. Journal of China Coal Society,2018,43(7):1789-1800.
[4]齐庆新,潘一山,舒龙勇,等.煤矿深部开采煤岩动力灾害多尺度分源防控理论与技术架构[J].煤炭学报,2018,43(7):1801-1810.QI Qingxin,PAN Yishan,SHU Longyong,et al.Theory and technical framework of prevention and control with different sources in multiscales for coal and rock dynamic in deep mining of coal mines[J].Journal of China Coal Society,2018,43(7):1801-1810.
[5]王家臣,张剑,姬刘亭,等.两硬条件下大采高综采老顶初次垮落力学模型研究[J].岩石力学与工程学报,2005,24(S1):5037-5042.WANG Jiachen,ZHANG Jian,JI Liuting,et al. Study on mechanics model of the first cave in main roof for the large cutting height fully mechanized mining under the two hard conditions[J].Journal of China Coal Society,2005,24(S1):5037-5042.
[6]陈忠辉,谢和平,李全生.长壁工作面采场围岩铰接薄板组力学模型研究[J].煤炭学报,2005,30(2):172-176.CHEN Zhonghui,XIE Heping,LI Quansheng. Study on plate group mechanical model for main roof of longwall face[J].Journal of China Coal Society,2005,30(2):172-176.
[7]缪协兴,钱鸣高.超长综放工作面覆岩关键层破断特征及对采场矿压的影响[J].岩石力学与工程学报,2003,22(1):45-47.MIAO Xiexing,QIAN Minggao. Broken feature of key strata and its influence on rock pressure in super-length fully-mechanized coal face[J].Chinese Journal of Rock Mechanics and Engineering,2003,22(1):45-47.
[8]刘畅,刘正和,张俊文,等.工作面长度对覆岩空间结构演化及大采高采场矿压规律的影响[J].岩土力学,2018,39(2):691-698.LIU Chang,LIU Zhenghe,ZHANG Junwen,et al. Effect of mining face length on the evolution of spatial structure of overlying strata and the law of underground pressure in large mining height face[J].Rock and Soil Mechanics,2018,39(2):691-698.
[9]哈秋舲,李建林,张永兴,等.节理岩体卸荷非线性岩体力学[M].北京:中国建筑工业出版社.
[10] LI X,HUAI Z,KONIETZKY H,et al.A numerical study of brittle failure in rocks with distinct microcrack characteristics[J].International Journal of Rock Mechanics and Mining Sciences,2018,106:289-299.
[11] LI Zhiyu,WANG Mingyu,ZHAO Jianhui,et al.Analysis on intersections between fractures by parallel computation[J].International Journal of Coal Science&Technology,2014,1(3):356-363.
[12]陈明祥.弹塑性力学[M].北京:科学出版社.
[13]钱鸣高,石平五,许家林.矿山压力与闫岑控制[M].徐州:中国矿业大学出版社.
[14] PYTEL Witold,SWITO N`Joanna,WOJCIK Adrian. The effect of mining face’s direction on the observed seismic activity[J].International Journal of Coal Science&Technology,2016,3(3):322-329.
[15] YANG Ke,HE Xiang,DOU Litong,et al.Experimental investigation into stress-relief characteristics with upward large height and upward mining under hard thick roof[J]. International Journal of Coal Science&Technology,2015,2(1):91-96.
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