细观特征对片岩起裂应力与裂纹扩展各向异性的影响
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摘要
压缩作用下,含片理面脆性片岩的渐进破坏表现出各向异性。为探讨片岩起裂应力与裂纹扩展各向异性特征及其与岩石细观因素的相关性,选取3类石英云母片岩样品,首先开展岩样的细观试验,并定量分析3类样品在微裂隙(孔隙)的细观特征方面的差异。试验发现样品中的云母矿物易定向聚集形成非均质层,微裂隙主要沿该矿物边缘定向展布,而在其他部位则表现出方向的不规则性。进而开展不同片理角α圆柱试样的单轴压缩试验,基于试样破坏形态与应力–应变曲线特征,通过断裂力学的理论分析,得出轴压斜交(α=30°)与垂直(α=90°)非均质层作用时,定向微裂隙与具有优势角的不规则微裂隙(孔隙)分别控制着岩石的起裂;云母矿物的边缘弱面是否对裂纹扩展具有导向、促进作用,与加载方向密切相关,由此造成不同片理角试样宏观剪切破坏形态的差异。应力、应变数据的统计分析结果与细观数据表明,试样的起裂应力及起裂应力水平表现出较好的规律性,这与岩石的非均质特征、微裂隙(孔隙)特征(分布、数量、尺寸、性质)等相关。
The progressive failure of brittle schist with schistose planes shows anisotropy under compression loading. In order to study the anisotropic properties of crack initiation stress and crack propagation of schist and their correlations with micro factors,three types of quartz mica schist samples were selected. Firstly,the optical section analysis of these samples was carried out,and the differences among the characteristics of microfissures(pores) of three type samples were quantitatively analyzed. The results show that the mica minerals in the samples are easy to form heterogeneous layers by directional aggregation,and that the micro-fissures are mainly distributed along the edge of the mineral while the developmental direction of the defects in other parts is irregular.Then,uniaxial compression tests were performed on cylindrical specimens with different schistose angles,and the failure morphology and stress-strain curve characteristics of the specimens were investigated. Theoretical analysis of fracture mechanics shows that,when the compression loading is oblique to( α =30°) and perpendicular to( α =90°) the heterogeneous layer,the initiation of rock fracture is respectively controlled by the directional micro-fissures and the irregular micro-fissures(pores) with dominant angles. The guiding and promoting effect of the weak edge of directionally aggregated minerals on crack growth is closely dependent on the loading direction,which results in the difference of macro shear failure modes of specimens with different schistose angles.Statistical analysis results of stress and strain data as well as the data reflecting micro properties show that the initiation stress and the initiation stress level of specimens have good regularity,which is related to the heterogeneity of rocks and the characteristics of micro-fissures(pores) such as distribution,quantity,size and nature.
The progressive failure of brittle schist with schistose planes shows anisotropy under compression loading. In order to study the anisotropic properties of crack initiation stress and crack propagation of schist and their correlations with micro factors,three types of quartz mica schist samples were selected. Firstly,the optical section analysis of these samples was carried out,and the differences among the characteristics of microfissures(pores) of three type samples were quantitatively analyzed. The results show that the mica minerals in the samples are easy to form heterogeneous layers by directional aggregation,and that the micro-fissures are mainly distributed along the edge of the mineral while the developmental direction of the defects in other parts is irregular.Then,uniaxial compression tests were performed on cylindrical specimens with different schistose angles,and the failure morphology and stress-strain curve characteristics of the specimens were investigated. Theoretical analysis of fracture mechanics shows that,when the compression loading is oblique to( α =30°) and perpendicular to( α =90°) the heterogeneous layer,the initiation of rock fracture is respectively controlled by the directional micro-fissures and the irregular micro-fissures(pores) with dominant angles. The guiding and promoting effect of the weak edge of directionally aggregated minerals on crack growth is closely dependent on the loading direction,which results in the difference of macro shear failure modes of specimens with different schistose angles.Statistical analysis results of stress and strain data as well as the data reflecting micro properties show that the initiation stress and the initiation stress level of specimens have good regularity,which is related to the heterogeneity of rocks and the characteristics of micro-fissures(pores) such as distribution,quantity,size and nature.
引文
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[6]周辉,孟凡震,卢景景,等.硬岩裂纹起裂强度和损伤强度取值方法探讨[J].岩土力学,2014,35(4):913-918.(ZHOU Hui,MENGFanzhen,LU Jingjing,et al.Discussion on methods for calculating crack initiation strength and crack damage strength for hard rock[J].Rock and Soil Mechanics,2014,35(4):913-918.(in Chinese))
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[10]刘泉声,魏莱,刘学伟,等.基于Griffith强度理论的岩石裂纹起裂经验预测方法研究[J].岩石力学与工程学报,2017,36(7):1 561-1 569.(LIU Quansheng,WEI Lai,LIU Xuewei,et al.A revised empirical method for predicting crack initiation based on Griffith strength criterion[J].Chinese Journal of Rock Mechanics and Engineering,2017,36(7):1 561-1 569.(in Chinese))
[11]周家文,徐卫亚,石崇.基于破坏准则的岩石压剪断裂判据研究[J].岩石力学与工程学报,2007,26(6):1 194-1 201.(ZHOU Jiawen,XU Weiya,SHI Chong.Investigation on compression-shear fracture criterion of rock based on failure criteria[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(6):1 194-1 201.(in Chinese))
[12]李银平,伍佑伦,杨春和.岩石类材料滑动裂纹模型[J].岩石力学与工程学报,2007,26(2):278-284.(LI Yinping,WU Youlun,YANG Chunhe.Comparison of sliding crack models for rock-like materials[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(2):278-284.(in Chinese))
[13]SHARAFISAFA M,NAZEM M.Application of the distinct element method and the extended finite element method in modelling cracks and coalescence in brittle materials[J].Computational Materials Science,2014,91(2):102-121.
[14]黄丹,李小青.基于微裂纹发育特性的大理岩特征强度数值模拟研究[J].岩土力学,2017,38(1):253-262.(HUANG Dan,LIXiaoqing.Numerical simulation research on characteristic strength of marble based on development of microcrack[J].Rock and Soil Mechanics,2017,38(1):253-262.(in Chinese))
[15]侯振坤,杨春和,孙书伟,等.板状页岩单轴压缩实验及断裂力学分析[J].煤炭学报,2017,42(5):1 251-1 257.(HOU Zhenkun,YANG Chunhe,SUN Shuwei,et al.Experimental study and fracture mechanics analysis of plate shale under uniaxial compression[J].Journal of China Coal Society,2017,42(5):1 251-1 257.(in Chinese))
[16]熊飞,靖洪文,苏海健,等.尖端相交裂隙砂岩强度与破裂演化特征试验研究[J].煤炭学报,2017,42(4):886-895.(XIONG Fei,JING Hongwen,SU Haijian,et al.Strength and fracture behaviors of sandstone samples containing intersect fissures under uniaxial compression[J].Journal of China Coal Society,2017,42(4):886-895.(in Chinese))
[17]李德行,王恩元,李楠,等.单轴压缩下宏观裂纹倾角对煤体特性影响研究[J].岩石力学与工程学报,2017,36(增1):3 206-3 213.(LI Dexing,WANG Enyuan,LI Nan,et al.Research on the coal characteristics of macro-crack dip angles under uniaxial compression[J].Chinese Journal of Rock Mechanics and Engineering,2017,36(Supp.1):3 206-3 213.(in Chinese))
[18]MARTIN C D,CHANDLER N A.The progressive fracture of Lac du Bonnet granite[J].International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts,1994,31(6):643-659.
[19]李莹,陈亮,刘建锋,等.饱水与晶体粒度对北山花岗岩断裂韧度影响的试验研究[J].岩石力学与工程学报,2018,37(增1):3 169-3 177.(LI Ying,CHEN Liang,LIU Jianfeng,et al.Experimental study on influence of saturation process and grain size on the fracture toughness of the Beishan granite[J].Chinese Journal of Rock Mechanics and Engineering,2018,37(增1):3 169-3 177.(in Chinese))
[20]张晓平,王思敬,韩庚友,等.岩石单轴压缩条件下裂纹扩展试验研究--以片状岩石为例[J].岩石力学与工程学报,2011,30(9):1 772-1 781.(ZHANG Xiaoping,WANG Sijing,HAN Gengyou,et al.Crack propagation study of rock based on uniaxial compressive test-a case study of schistose rock[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(9):1 772-1 781.(in Chinese))
[21]王宇,李晓,武艳芳,等.脆性岩石起裂应力水平与脆性指标关系探讨[J].岩石力学与工程学报,2014,33(2):264-275.(WANGYu,LI Xiao,WU Yanfang,et al.Research on relationship between crack initiation stress level and brittleness indices for brittle rocks[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(2):264-275.(in Chinese))
[22]赵程,于志敏,王文东,等.基于单轴压缩的岩体破坏机制细观试验研究[J].岩石力学与工程学报,2016,35(12):2 490-2 498.(ZHAO Cheng,YU Zhimin,WANG Wendong,et al.Meso-experimental study of failure mechanism of rock based on uniaxial compression test[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(12):2 490-2 498.(in Chinese))
[23]尹晓萌.武当群片岩的各向异性研究及其在隧道支护中的应用[博士学位论文][D].武汉:中国地质大学,2017.(YIN Xiaomeng.The Anisotropy of Wudang Group Schist and its application in tunnel support[Ph.D.Thesis][D].Wuhan:China University of Geosciences,2017.(in Chinese))
[24]李世愚.岩石断裂力学导论[M].合肥:中国科学技术大学出版社,2010:100-161.(LI Shiyu.Introduction of rock fracture mechanics[M].Hefei:University of Science and Technology China press,2010:100-161.(in Chinese))
[25]何江达,范景伟,张建海.关于“节理岩体拉剪断裂与强度研究”一文的几点看法[J].岩石力学与工程学报,1999,18(4):479.(HEJiangda,FAN Jingwei,ZHANG Jianhai.Views on the study of tensile shear fracture and strength of jointed rock mass[J].Chinese Journal of Rock Mechanics and Engineering,1999,18(4):479.(in Chinese))
[26]AMANN F,?MERü,KAISER P K.Crack initiation and crack propagation in heterogeneous sulfate-rich clay rocks[J].Rock Mechanics and Rock Engineering,2014,47(5):1 849-1 865.
[27]DIEDERICHS M S,KAISER P K,EBERHARDT E.Damage initiation and propagation in hard rock during tunnelling and the influence of near-face stress rotation[J].International Journal of Rock Mechanics and Mining Sciences,2004,41(5):785-812.
[28]NIANDOU H,SHAO J F,HENRY J P,et al.Laboratory investigation of the mechanical behaviour of Tournemire shale[J].International Journal of Rock Mechanics and Mining Sciences,1997,34(1):3-16.
[2]BIENIAWSKI Z T.Mechanism of brittle fracture of rock:part I-theory of the fracture process[J].International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts,1967,4(4):395-406.
[3]MARTIN C D.The effect of cohesion loss and stress path on brittle rock strength[J].Canadian Geotechnical Journal,1997,34(5):698-725.
[4]EBERHARDT E,STEAD D,STIMPSON B,et al.Identifying crack initiation and propagation thresholds in brittle rock[J].Canadian Geotechnical Journal,1998,35(2):222-233.
[5]NICKSIAR M,MARTIN C D.Evaluation of methods for determining crack initiation in compression tests on low-porosity rocks[J].Rock Mechanics and Rock Engineering,2012,45(4):607-617.
[6]周辉,孟凡震,卢景景,等.硬岩裂纹起裂强度和损伤强度取值方法探讨[J].岩土力学,2014,35(4):913-918.(ZHOU Hui,MENGFanzhen,LU Jingjing,et al.Discussion on methods for calculating crack initiation strength and crack damage strength for hard rock[J].Rock and Soil Mechanics,2014,35(4):913-918.(in Chinese))
[7]ERDOGAN F,SIH G C.On crack extension in plates under plane loading and transverse shear[J].Journal of Basic Engineering,ASME,1963,85(4):519-527.
[8]范景伟,何江达.含定向闭合断续节理岩体的强度特性[J].岩石力学与工程学报,1992,11(2):190-199.(FAN Jingwei,HE Jiangda.Strength characteristics of rock mass with directional closed intermittent joints[J].Chinese Journal of Rock Mechanics and Engineering,1992,11(2):190-199.(in Chinese))
[9]何江达,范景伟.含一组未闭合断续节理脆性岩体强度特性[J].四川大学学报:工程科学版,1990,54(6):57-64.(HE Jiangda,FANJingwei.Strength characteristics of brittle rock mass with a group of uninterrupted intermittent joints[J].Journal of Sichuan University:Engineering Science,1990,54(6):57-64.(in Chinese))
[10]刘泉声,魏莱,刘学伟,等.基于Griffith强度理论的岩石裂纹起裂经验预测方法研究[J].岩石力学与工程学报,2017,36(7):1 561-1 569.(LIU Quansheng,WEI Lai,LIU Xuewei,et al.A revised empirical method for predicting crack initiation based on Griffith strength criterion[J].Chinese Journal of Rock Mechanics and Engineering,2017,36(7):1 561-1 569.(in Chinese))
[11]周家文,徐卫亚,石崇.基于破坏准则的岩石压剪断裂判据研究[J].岩石力学与工程学报,2007,26(6):1 194-1 201.(ZHOU Jiawen,XU Weiya,SHI Chong.Investigation on compression-shear fracture criterion of rock based on failure criteria[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(6):1 194-1 201.(in Chinese))
[12]李银平,伍佑伦,杨春和.岩石类材料滑动裂纹模型[J].岩石力学与工程学报,2007,26(2):278-284.(LI Yinping,WU Youlun,YANG Chunhe.Comparison of sliding crack models for rock-like materials[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(2):278-284.(in Chinese))
[13]SHARAFISAFA M,NAZEM M.Application of the distinct element method and the extended finite element method in modelling cracks and coalescence in brittle materials[J].Computational Materials Science,2014,91(2):102-121.
[14]黄丹,李小青.基于微裂纹发育特性的大理岩特征强度数值模拟研究[J].岩土力学,2017,38(1):253-262.(HUANG Dan,LIXiaoqing.Numerical simulation research on characteristic strength of marble based on development of microcrack[J].Rock and Soil Mechanics,2017,38(1):253-262.(in Chinese))
[15]侯振坤,杨春和,孙书伟,等.板状页岩单轴压缩实验及断裂力学分析[J].煤炭学报,2017,42(5):1 251-1 257.(HOU Zhenkun,YANG Chunhe,SUN Shuwei,et al.Experimental study and fracture mechanics analysis of plate shale under uniaxial compression[J].Journal of China Coal Society,2017,42(5):1 251-1 257.(in Chinese))
[16]熊飞,靖洪文,苏海健,等.尖端相交裂隙砂岩强度与破裂演化特征试验研究[J].煤炭学报,2017,42(4):886-895.(XIONG Fei,JING Hongwen,SU Haijian,et al.Strength and fracture behaviors of sandstone samples containing intersect fissures under uniaxial compression[J].Journal of China Coal Society,2017,42(4):886-895.(in Chinese))
[17]李德行,王恩元,李楠,等.单轴压缩下宏观裂纹倾角对煤体特性影响研究[J].岩石力学与工程学报,2017,36(增1):3 206-3 213.(LI Dexing,WANG Enyuan,LI Nan,et al.Research on the coal characteristics of macro-crack dip angles under uniaxial compression[J].Chinese Journal of Rock Mechanics and Engineering,2017,36(Supp.1):3 206-3 213.(in Chinese))
[18]MARTIN C D,CHANDLER N A.The progressive fracture of Lac du Bonnet granite[J].International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts,1994,31(6):643-659.
[19]李莹,陈亮,刘建锋,等.饱水与晶体粒度对北山花岗岩断裂韧度影响的试验研究[J].岩石力学与工程学报,2018,37(增1):3 169-3 177.(LI Ying,CHEN Liang,LIU Jianfeng,et al.Experimental study on influence of saturation process and grain size on the fracture toughness of the Beishan granite[J].Chinese Journal of Rock Mechanics and Engineering,2018,37(增1):3 169-3 177.(in Chinese))
[20]张晓平,王思敬,韩庚友,等.岩石单轴压缩条件下裂纹扩展试验研究--以片状岩石为例[J].岩石力学与工程学报,2011,30(9):1 772-1 781.(ZHANG Xiaoping,WANG Sijing,HAN Gengyou,et al.Crack propagation study of rock based on uniaxial compressive test-a case study of schistose rock[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(9):1 772-1 781.(in Chinese))
[21]王宇,李晓,武艳芳,等.脆性岩石起裂应力水平与脆性指标关系探讨[J].岩石力学与工程学报,2014,33(2):264-275.(WANGYu,LI Xiao,WU Yanfang,et al.Research on relationship between crack initiation stress level and brittleness indices for brittle rocks[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(2):264-275.(in Chinese))
[22]赵程,于志敏,王文东,等.基于单轴压缩的岩体破坏机制细观试验研究[J].岩石力学与工程学报,2016,35(12):2 490-2 498.(ZHAO Cheng,YU Zhimin,WANG Wendong,et al.Meso-experimental study of failure mechanism of rock based on uniaxial compression test[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(12):2 490-2 498.(in Chinese))
[23]尹晓萌.武当群片岩的各向异性研究及其在隧道支护中的应用[博士学位论文][D].武汉:中国地质大学,2017.(YIN Xiaomeng.The Anisotropy of Wudang Group Schist and its application in tunnel support[Ph.D.Thesis][D].Wuhan:China University of Geosciences,2017.(in Chinese))
[24]李世愚.岩石断裂力学导论[M].合肥:中国科学技术大学出版社,2010:100-161.(LI Shiyu.Introduction of rock fracture mechanics[M].Hefei:University of Science and Technology China press,2010:100-161.(in Chinese))
[25]何江达,范景伟,张建海.关于“节理岩体拉剪断裂与强度研究”一文的几点看法[J].岩石力学与工程学报,1999,18(4):479.(HEJiangda,FAN Jingwei,ZHANG Jianhai.Views on the study of tensile shear fracture and strength of jointed rock mass[J].Chinese Journal of Rock Mechanics and Engineering,1999,18(4):479.(in Chinese))
[26]AMANN F,?MERü,KAISER P K.Crack initiation and crack propagation in heterogeneous sulfate-rich clay rocks[J].Rock Mechanics and Rock Engineering,2014,47(5):1 849-1 865.
[27]DIEDERICHS M S,KAISER P K,EBERHARDT E.Damage initiation and propagation in hard rock during tunnelling and the influence of near-face stress rotation[J].International Journal of Rock Mechanics and Mining Sciences,2004,41(5):785-812.
[28]NIANDOU H,SHAO J F,HENRY J P,et al.Laboratory investigation of the mechanical behaviour of Tournemire shale[J].International Journal of Rock Mechanics and Mining Sciences,1997,34(1):3-16.