煤炭深部开采界定及采动响应分析
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摘要
科学界定深部是深部开采理论发展与技术实践的重要问题,探讨适于我国煤炭现代开采实践的深部开采界定方法具有重要意义。为此,综合考虑我国煤矿矿区深部岩石、地下水环境和现代开采方式,将区域应力场与采动应力场分析相结合,基于我国地壳浅部、煤矿矿区深部准静水应力状态分析,进一步研究我国煤矿矿区的深部界定、基于不同矿区煤岩状态(岩性及组合、含水性等)差异的相对深部界定和开采时动态深部区确定方法。研究表明,原岩初始状态和开采方式共同决定了采动力学状态及变化规律和其他伴生状态变化。基于深部与浅部的力学状态差异,将深部开采界定为在高地应力环境且具有采动非线性力学响应的煤岩体空间实施的采矿活动;依据我国煤矿矿区应力场统计变化规律和准静水应力状态分析,采用平均侧压系数K_(av)(即:水平最大主应力和最小主应力的平均值与垂直应力之比)确定煤矿矿区深部临界深度,结合我国中东部深部开采实践确定的参考深部临界深度H_m为850～900 m;基于不同矿区原岩差异性(岩性及组合、含水性等),建立了不同初始状态时实际深部临界深度H_s(简称为视临界深度)与H_m比较模型,分析发现采动煤层覆岩越软和含水性越强,其深部临界深度越浅(或"趋浅"),降低幅度可达30%～50%;基于开采"应力拱"现象构建了深部采动应力状态K_(av)模型和H_s计算方法,采动响应分析表明:开采工作面切眼外侧及采场前端局部H_s呈变浅→变深→正常的变化特征(或"端部效应"),工作面中部区域呈变浅趋势(或"趋浅"),采高越大其H_s"趋浅"效应越显著,而随工作面推进距离增加端部效应变小;东、中、西部典型矿区H_s与H_m比较表明:东部矿区H_s偏深,中部矿区深度相近,西部(陕、蒙等)地下水丰富的矿区偏浅,在500～600 m即可达到实际深部临界深度,采深400～500 m时大采高工作面两端外侧局部也可显现深部力学状态。研究基于我国深部岩石力学研究成果和开采条件及现代开采方式,探讨提出的深部界定方法和结果,与已有深部开采理论研究与实践成果比较证实,该方法具有理论合理性和结果可靠性。
Scientific deep definition,especially the definition method of deep mining suitable for the modern mining practice,is a significant issue in developing the deep mining theory and technical practice. The deep rock,groundwater environment and modern mining methods in coal mining areas were comprehensively considered for the definition of coal deep mining. Based on the analysis of quasi-hydrostatic pressure environment in shallow crust and deep coal mine areas in China,a further study of deep definition of coal mining areas,the relative deep definition in different mining areas with the differences of coal and rock states(lithology and assemblage,water content,etc.),and the determination method of dynamic deep areas in deep mining were focused. The research shows that the coupling action between the initial state of the original rock and the mining mode determines the mechanical response behavior and state of the original rock. The remarkable features of the deep mechanical state are the high stress environment and the non-linear mechanical response characteristics,which are the main causes of the basic state in many states and the associated disasters in deep mining. The deep mining is then defined as a special mining activity in the space of coal and rock mass with high stress environment and non-linear mechanical response. After analyzing the regional tendency of shallow crust and local stress fields of coal mining areas with the depth in China,average lateral pressure coefficientK_(av)(i. e.the ratio of the average value of horizontal maximum principal stress and minimum principal stress to vertical stress) is selected as a basic parameter for the deep criteria of coal mine areas. By combining the deep mining practice in the eastern and middle part of China,the depth of 850-900 m is appropriately considered as reference critical depth of deep coal mining in China(shortly DCM ofHm). Based on the difference of original rock in different mining areas(rock lithology,structure,water content,etc.),a comparison model betweenHs(i. e. the actual or visual DCM) and Hmis established,varied with initial protolithic states. Analyzing the relative change of the different mining geological situations,the result reveals that the softer the rock and the stronger the water content,the shallower the visual DCM becomes(or "shallowing"),even the depth reduction up to 30% ～50%. Based on the phenomenon of "stress arch"in mining,the K_(av)model and theHscalculation method are constructed for the description of deep mining stress state.The modeling shows that the local stress andHsfrom the cut position of working face to the external section of the propulsion are the characteristic of the "end effect" changes from shallow→deep→normal,and the stress in the central area of working face is in a "lighter" state(or "shallowing"). The higher the mining height,the more pronounced the"lighter" state. The "end effect" tends to be gradually slowed down and weaken with the increase of the propulsion distance. The comparison of the critical depth from the typical mining areas shows that the depth in the eastern mining is deeper than the reference DCM,similar in the central mining area and less in the western mining area rich in groundwater(Shaanxi,Inner-Mongolia),actually so shallow as to 500-600 m. Nevertheless,the local deep mechanical anomaly could be found in the "end effect" area,in the mining depth of 400-500 m with a greater mining height using large-sized modern mining method. Based on the research results of deep rock mechanics and modern coal mining practices,the deep definition methods are proposed and discussed,combined with the characteristics of resource endowment in different mining regions of China and deep mining practice. By comparing with the existing related research and practice results,the method is proved to be rational in theory and its result is reliable. The method is useful to the research and practice of deep coal mining in China.
Scientific deep definition,especially the definition method of deep mining suitable for the modern mining practice,is a significant issue in developing the deep mining theory and technical practice. The deep rock,groundwater environment and modern mining methods in coal mining areas were comprehensively considered for the definition of coal deep mining. Based on the analysis of quasi-hydrostatic pressure environment in shallow crust and deep coal mine areas in China,a further study of deep definition of coal mining areas,the relative deep definition in different mining areas with the differences of coal and rock states(lithology and assemblage,water content,etc.),and the determination method of dynamic deep areas in deep mining were focused. The research shows that the coupling action between the initial state of the original rock and the mining mode determines the mechanical response behavior and state of the original rock. The remarkable features of the deep mechanical state are the high stress environment and the non-linear mechanical response characteristics,which are the main causes of the basic state in many states and the associated disasters in deep mining. The deep mining is then defined as a special mining activity in the space of coal and rock mass with high stress environment and non-linear mechanical response. After analyzing the regional tendency of shallow crust and local stress fields of coal mining areas with the depth in China,average lateral pressure coefficientK_(av)(i. e.the ratio of the average value of horizontal maximum principal stress and minimum principal stress to vertical stress) is selected as a basic parameter for the deep criteria of coal mine areas. By combining the deep mining practice in the eastern and middle part of China,the depth of 850-900 m is appropriately considered as reference critical depth of deep coal mining in China(shortly DCM ofHm). Based on the difference of original rock in different mining areas(rock lithology,structure,water content,etc.),a comparison model betweenHs(i. e. the actual or visual DCM) and Hmis established,varied with initial protolithic states. Analyzing the relative change of the different mining geological situations,the result reveals that the softer the rock and the stronger the water content,the shallower the visual DCM becomes(or "shallowing"),even the depth reduction up to 30% ～50%. Based on the phenomenon of "stress arch"in mining,the K_(av)model and theHscalculation method are constructed for the description of deep mining stress state.The modeling shows that the local stress andHsfrom the cut position of working face to the external section of the propulsion are the characteristic of the "end effect" changes from shallow→deep→normal,and the stress in the central area of working face is in a "lighter" state(or "shallowing"). The higher the mining height,the more pronounced the"lighter" state. The "end effect" tends to be gradually slowed down and weaken with the increase of the propulsion distance. The comparison of the critical depth from the typical mining areas shows that the depth in the eastern mining is deeper than the reference DCM,similar in the central mining area and less in the western mining area rich in groundwater(Shaanxi,Inner-Mongolia),actually so shallow as to 500-600 m. Nevertheless,the local deep mechanical anomaly could be found in the "end effect" area,in the mining depth of 400-500 m with a greater mining height using large-sized modern mining method. Based on the research results of deep rock mechanics and modern coal mining practices,the deep definition methods are proposed and discussed,combined with the characteristics of resource endowment in different mining regions of China and deep mining practice. By comparing with the existing related research and practice results,the method is proved to be rational in theory and its result is reliable. The method is useful to the research and practice of deep coal mining in China.
引文
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[3]蓝航,陈东科,毛德兵.我国煤矿深部开采现状及灾害防治分析[J].煤炭科学技术,2016,44(1):39-46.LAN Hang,CHEN Dongke,MAO Debing.Current status of deep mining and disaster prevention in China[J].Coal Science and Technology,2016,44(1):39-46.
[4]何满潮.深部开采工程岩石力学现状及其展望[A].第八次全国岩石力学与工程学术大会论文集[C].北京:科学出版社,2004:88-94.HE Manchao.Present Status and prospect of rock mechanics in deep mining engineering[A].Proceedings of the 8th National Academic Conference on Rock Mechanics and Engineering[C].Beijing:Science Press,2004:88-94.
[5]何满潮.深部软岩工程的研究进展与挑战[J].煤炭学报,2014,39(8):1409-1417.HE Manchao.Progress and challenges of soft rock engineering in depth[J].Journal of China Coal Society,2014,39(8):1409-1417.
[6]周宏伟,谢和平,左建平,等.赋存深度对岩石力学参数影响的实验研究[J].科学通报,2010,55(34):3276-3284.ZHOU Hongwei,XIE Heping,ZUO Jianping,et al.Experimental study on the influence of depth on rock mechanical parameters[J].Chinese Science Bulletin,2010,55(34):3276-3284.
[7]李鹏波,王金安.煤层上覆岩层力学性质随赋存深度变化试验[J].哈尔滨工业大学学报,2015,47(12):98-101.LI Pengbo,WANG Jinan.Experimental study on mechanical properties of overlying strata in coal seam with variation of occurrence depth[J].Journal of Harbin Institute of Technology,2015,47(12):98-101.
[8]蔡美峰,冀东,郭奇峰.基于地应力现场实测与开采扰动能量积聚理论的岩爆预测研究[J].岩石力学与工程学报,2013,32(10):1973-1980.CAI Meifeng,JI Dong,GUO Qifeng.Study of rockbust prediction based on in-situ stress measurement and theory of energy accumulation caused by mining disturbance[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(10):1973-1980.
[9]黎立云,谢和平,鞠杨,等.岩石可释放应变能及耗散能的实验研究[J].工程力学,2011,28(3):35-40.LI Liyun,XIE Heping,JU Yang,et al.Experimental study on the release of strain energy and dissipated energy from rocks[J].Engineering Mechanics,2011,28(3):35-40.
[10]钱七虎,李树忱.深部岩体工程围岩分区破裂化现象研究综述[J].岩石力学与工程学报,2008,27(6):1278-1284.QIAN Qihu,LI Shuchen.Summary of research on rupture phenomenon of surrounding rock division in deep rock mass engineering[J].Journal of Rock Mechanics and Engineering,2008,27(6):1278-1284.
[11]王明洋,宋华,郑大亮,等.深部巷道围岩的分区破裂机制及“深部”界定探讨[J].岩石力学与工程学报,2006,25(9):1771-1771.WANG Mingyang,SONG Hua,ZHEN Daliang,et al.Discussion on the divisional rupture mechanism and the definition of“deep”in surrounding rock of deep roadway[J].Journal of Rock Mechanics and Engineering,2006,25(9):1771-1771.
[12]谢广祥.综放工作面及其围岩宏观应力壳力学特征[J].煤炭学报,2005,30(3):309-313.XIE Guangxiang.Fully mechanized caving face and its macroscopic stress shell mechanical characteristics of surrounding rock[J].Journal of China Coal Sociaty,2005,30(3):309-313.
[13]杜锋,白海波.厚松散层薄基岩综放开采覆岩破断机理研究[J].煤炭学报,2012,37(7):1105-1110.DU Feng,BAI Haibo.Mechanism research of overlying strata activity with fully mechanized caving in thin bedrock with thick alluvium[J].Journal of China Coal Sociaty,2012,37(7):1105-1110.
[14]耿养谋.矿山开采覆岩应力拱演化规律研究[J].山东科技大学学报(自然科学版),2009,28(4):43-48.GENG Yangmou.Study on evolution law of stress arch of overlying strata in mines[J].Journal of Shandong University of Science and Technology(Natural Science),2009,28(4):43-48.
[15]王艳华,崔效锋,胡幸平,等.基于原地应力测量数据的中国大陆地壳上部应力状态研究[J].地球物理学报,2012,55(9):3016-3027.WANG Yanhua,CUI Xiaofeng,HU Xingping,et al.Study on the stress state in upper crust of China mainland based on in-situ stress measurements[J].Chinese Gyophysices,2012,55(9):3016-3027.
[16]李鹏,苗胜军.中国煤矿矿区地应力场特征与断层活动性分析[J].煤炭学报,2016,41(S2):319-329.LI Peng,MIAO Shengjun.Analysis of the characteristics of in situ stress field and fault activity in the coal mining area of China[J].Journal of China Coal Society,2016,41(S2):319-329.
[17]康红普,深部煤矿应力分布特征及巷道围岩控制技术[J].煤炭科学技术,2013,41(9):12-17.KANG Hongpu.Stress distribution characteristics of deep coal mine and surrounding rock control technology of roadway[J].Coal Science and Technology,2013,41(9):12-17.
[18]谢和平,高峰,鞠杨.深部岩体力学研究与探索[J].岩石力学与工程学报,2015,34(11):2161-2178.XIE Heping,GAO Feng,JU Yang.Research and development of rock mechanics in deep ground engineering[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(11):2161-2178.
[19]何满潮.深部的概念体系及工程评价指标[J].岩石力学与工程学报,2005,24(16):2854-2858.HE Manchao.Deep conceptual system and engineering evaluation indicators[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(16):2854-2858.
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