采动覆岩破断裂隙的贯通度研究
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摘要
为了判定采场隔水关键层和计算导水裂隙带高度,进行了覆岩采动导水裂隙分布特征的相似模拟实验和力学分析.提出了破断裂隙贯通度的概念和计算公式.试验结果表明,采场覆岩裂隙带上位岩层的回转变形空间较小,且由于岩层刚度和厚度的差异,薄岩层会完全破断;但坚硬厚岩层破断裂隙未贯通,没有形成竖向"导水、导气"裂隙.为了描述岩层的破断程度及破断裂隙导水能力的强弱岩层破断裂隙的贯通度随其下自由空间的增大而增大,且存在自由空间阀值,大于其阀值时则增加缓慢并趋于1;随岩层厚度增大,起裂时岩层破断裂缝的张开角度减小;岩层破断裂隙的贯通度随裂纹尖端临界张开位移的增大而呈线性减小,随岩层周期破断距的增大也呈近似线性减小.
Simulation and mechanical analysis were used to study the distribution of water conducting fissures induced in overlying strata by mining.The concept of degrees of fracture-fissure is presented.The results show thin strata completely fracture but hard,thick strata fracture incompletely.Incompletely fractured strata are not capable of vertically passing water or gas.Different stiffness and thickness of the upper strata affect the deformation in the fracture zone.The degree of fracture-fissure increases as the free space in the fracture zone increases.There is a gradual increase that tends to one as the free space exceeds some threshold value.As the strata thickness increases the open angle of the starting fracture-fissure decreases.The degree of fracture-fissure is linearly reduced along the crack tip at the critical opening displacement.It is also approximately linearly decreasing with an increase in the periodic fracture distance in the strata.
Simulation and mechanical analysis were used to study the distribution of water conducting fissures induced in overlying strata by mining.The concept of degrees of fracture-fissure is presented.The results show thin strata completely fracture but hard,thick strata fracture incompletely.Incompletely fractured strata are not capable of vertically passing water or gas.Different stiffness and thickness of the upper strata affect the deformation in the fracture zone.The degree of fracture-fissure increases as the free space in the fracture zone increases.There is a gradual increase that tends to one as the free space exceeds some threshold value.As the strata thickness increases the open angle of the starting fracture-fissure decreases.The degree of fracture-fissure is linearly reduced along the crack tip at the critical opening displacement.It is also approximately linearly decreasing with an increase in the periodic fracture distance in the strata.
引文
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[3]钱鸣高,缪协兴,许家林,等.岩层控制的关键层理论[M].徐州:中国矿业大学出版社,2003.
[4]黄炳香,刘长友,程庆迎,等.基于瓦斯抽放的顶板冒落规律模拟试验研究[J].岩石力学与工程学报,2006,25(11):2200-2207.HUANG Bing-xiang,LI U Chang-you,CHENG Qing-ying,et al.Si mulation experi mental study on law of gob roof fall based on gas drainage[J].Chi-nese Journal of Rock Mechanics and Engineering,2006,25(11):2200-2207.
[5]KI MJ M,PARIZEK R R,ELSWORTHD.Evalua-tion of fully-coupled strata deformation and groundw-ater flowin response to longwall mining[J].Interna-tional Journal of Rock Mechanics and Mining Sci-ences,1997,34(8):1187-1199.
[6]杨天鸿,唐春安,谭志宏,等.岩体破坏突水模型研究现状及突水预测预报研究发展趋势[J].岩石力学与工程学报,2007,26(2):268-279.YANG Tian-hong,TANG Chun-an,TANZhi-hong,et al.State of the art of inrush models in rock mass failure and developing trend for prediction and fore-cast of groundwater inrush[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(2):268-279.
[7]WANGJ A,PARK H D.Coal mining above a con-fined aquifer[J].International Journal of Rock Me-chanics and Mining Sciences,2003,40(4):537-551.
[8]缪协兴,浦海,白海波.隔水关键层原理及其在保水采煤中的应用研究[J].中国矿业大学学报,2008,37(1):1-4.MIAO Xie-xing,PU Hai,BAI Hai-bo.Principle of water-resisting key strata andits applicationin water-preserved mining[J].Journal of China University of Mining&Technology,2008,37(1):1-4.
[9]郭广礼,缪协兴,张振南.老采空区破裂岩体变形性质研究[J].科学技术与工程,2002,2(5):44-47.GUO Guang-li,MIAO Xie-xing,ZHANG Zhen-nan.Research on rock mass deformation characteristics of longwall goaf[J].Science Technology and Engineer-ing,2002,2(5):44-47.
[10]邓喀中,周鸣,谭志祥,等.采动岩体破裂规律的试验研究[J].中国矿业大学学报,1998,27(3):261-264.DENG Ka-zhong,ZHOU Ming,TANZhi-xiang,et al.Study on laws of rockmass breaking induced by mining[J].Journal of China University of Mining&Technology,1998,27(3):261-264.
[11]杨成永,王冲,陈至达.岩层断裂的最大转动梯度准则及其在构造地质中的应用[J].地壳形变与地震,1995,15(4):1-7.YANG Cheng-yong,WANG Chong,CHEN Zhi-da.Maxi mal microrotation gradient criterion and its applications in tectonic geology[J].Crustal Deform-ation and Earthquake,1995,15(4):1-7.
[12]朱锡,华天瑞.梁在纯弯曲力矩作用下的动态塑性断裂[J].力学学报,1989,21(2):241-244.ZHU Xi,HUA Tian-rui.Dynamic plastic fracture of a beamin pure bending[J].Acta Mechanica Sini-ca,1989,21(2):241-244.
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