(1. Institute of Deep Earth Science and Green Energy，Shenzhen University，Shenzhen，Guangdong 518060，China；
2. College of Civil and Transportation Engineering，Shenzhen University，Shenzhen，Guangdong 518060，China；
3. College of Water Resource and Hydropower，Sichuan University，Chengdu，Sichuan 610065，China)
Abstract：To study the effect of flaw inclination angle on strain evolution and failure behavior of flawed rocks，a set of compressive-shear tests were conducted with red sandstones containing a single pre-existing flaw. The full-field strain evolution of flawed specimen was monitored，recorded and analyzed using digital image correlation (DIC) technique，a criterion was proposed to determine initiation position of wing crack under compressive-shear loading，and the fractography of rock fractures were examined using scanning electron microscope(SEM). The results show that the degree of deterioration of the peak compression-shear force on the specimen by pre-existing flaw depends on its flaw inclination angle，and the strain evolution processes of the flawed-specimens can be divided into four typical stages，including compaction stage，quasi-elastic stage，crack propagation and coalescence stage，and the post-peak stage. Based on the crack initiation locations，five typical strain concentration zones were summarized，including strain bands of wing crack，anti-wing crack，secondary crack，normal and tangential edge cracks，respectively. The DIC analysis of strain evolution at several key points of some typical specimens shows that the initiation and propagation of cracks were dominated by a mixed tension-shearing effect. A novel crack dominate parameter(CDP) was proposed to quantify the degree of tension and shearing effects on crack initiation mechanism. The results show that with increase of flaw inclination angle，the shearing effect on crack initiation mechanism of the anti-wing crack gradually decreases，while its effect on secondary crack increases. When the flaw inclination angle over 30°，the mixed tension-shearing effect gradually dominates the initiation mechanism of wing cracks. Based on circular maximum theory，a theoretical criterion was proposed to determine the initiation position of wing cracks under compressive-shear loading，and the theoretical predictions agree well with the experimental results. The SEM analysis of some typical fracture surfaces shows that the fractography of wing cracks changed from rough to relatively smooth when the flaw inclination angle increased from 0° to 30°，indicating enhancement of the tensile extent，while the fractography of anti-wing cracks，secondary cracks and edge cracks were presented in layered，parallel and strip forms，respectively. The findings of this study could facilitate understanding of cracking behavior of fractured rock mass subjected to compressive-shear loading.
陈家嵘1，2，周昌台1，2，3，周 韬1，2，朱建波1，2，谢和平1，2，3. 压剪荷载下含单一裂隙砂岩的应变演化与破坏特征研究[J]. 岩石力学与工程学报, 2023, 42(7): 1743-1758.
CHEN Jiarong1，2，ZHOU Changtai1，2，3，ZHOU Tao1，2，ZHU Jianbo1，2，XIE Heping1，2，3. Experimental study on strain evolution and failure behavior of sandstone containing a single pre-existing flaw under compressive-shear loading#br#. , 2023, 42(7): 1743-1758.
[1] 林 鹏，黄凯珠，王仁坤，等. 不同角度单裂纹缺陷试样的裂纹扩展与破坏行为[J]. 岩石力学与工程学报，2005，24(增2)：5 652–5 657.(LIN Peng，HUANG Kaizhu，WANG Renkun，et al. Crack growth mechanism and failure behavior of specimen containing single flaw with different angles[J]. Chinese Journal of Rock Mechanics and Engineering，2005，24(Supp.2)：5 652–5 657.(in Chinese))
[2] ZHU J B，ZHOU T，LIAO Z Y，et al. Replication of internal defects and investigation of mechanical and fracture behaviour of rock using 3D printing and 3D numerical methods in combination with X-ray computerized tomography[J]. International Journal of Rock Mechanics and Mining Sciences，2018，106：198–212.
[3] 朱万成，唐春安. 岩板中混合裂纹扩展过程的数值模拟[J]. 岩土工程学报，2000，22(2)：231–234.(ZHU Wangcheng，TANG Chun?an. Numerical simulation on the propagation processes of mixed mode cracks in rock plates[J]. Chinese Journal of Geotechnical Engineering. 2000，22(2)：231–234.(in Chinese))
[4] ZHOU T，ZHU J B，JU Y，et al. Volumetric fracturing behavior of 3D printed artificial rocks containing single and double 3D internal flaws under static uniaxial compression[J]. Engineering Fracture Mechanics. 2019，205：190–204.
[5] 陈卫忠，李术才，邱祥波，等. 岩石裂纹扩展的实验与数值分析研究[J]. 岩石力学与工程学报，2003，22(1)：18–23.(CHEN Weizhong，LI Shucai，QIU Xiangbo，et al. Experimental and numerical research on crack propagation in rock under compression[J]. Chinese Journal of Rock Mechanics and Engineering，2003，22(1)：18–23.(in Chinese))
[6] 李地元，成腾蛟，周 韬，等. 冲击载荷作用下含孔洞大理岩动态力学破坏特性试验研究[J]. 岩石力学与工程学报，2015，34(2)：249–260.(LI Diyuan，CHENG Tengjiao，ZHOU Tao，et al. Experimental study of the dynamic strength and fracturing characteristics of marble specimens with a single hole under impact loading[J]. Chinese Journal of Rock Mechanics and Engineering，2015，34(2)：249–260.(in Chinese))
[7] SAGONG M，BOBET A. Coalescence of multiple flaws in a rock-model material in uniaxial compression[J]. International Journal of Rock Mechanics and Mining Sciences，2002，39(2)：229–241.
[8] WONG L N Y，EINSTEIN H H. Crack coalescence in molded gypsum and carrara marble：Part 1. Macroscopic observations and interpretation[J]. Rock Mechanics and Rock Engineering，2009，42(3)：475–511.
[9] WONG R H C，CHAU K T. Crack coalescence in a rock-like material containing two cracks[J]. International Journal of Rock Mechanics and Mining Sciences，1998，35(2)：147–164.
[10] 杨圣奇，刘相如，李玉寿. 单轴压缩下含孔洞裂隙砂岩力学特性试验分析[J]. 岩石力学与工程学报，2012，31(增2)：3 539–3 546. (YANG Shengqi，LIU Xiangru，LI Yushou. Experimental analysis of mechanical behavior of sandstone containing hole and fissure under uniaxial compression[J]. Chinese Journal of Rock Mechanics and Engineering，2012，31(Supp.2)：3 539–3 546.(in Chinese))
[11] 李银平，王元汉，陈龙珠，等. 含预制裂纹大理岩的压剪试验分析[J]. 岩土工程学报，2004，26(1)：120–124.(LI Yinping，WANG Yuanhan，CHEN Longzhu，et al. Experimental research on pre-existing cracks in marble under compression[J]. Chinese Journal of Geotechnical Engineering，2004，26(1)：120–124.(in Chinese))
[12] 潘鹏志，丁梧秀，冯夏庭，等. 预制裂纹几何与材料属性对岩石裂纹扩展的影响研究[J]. 岩石力学与工程学报，2008，27(9)：1 882–1 889.(PAN Pengzhi，DING Wuxiu，FENG Xiating，et al. Research on influence of pre-existing crack geometrical and material properties on crack propagation in rocks[J]. Chinese Journal of Rock Mechanics and Engineering，2008，27(9)：1 882–1 889.(in Chinese))
[13] 张 波，李术才，杨学英，等. 含交叉多裂隙类岩石材料单轴压缩力学性能研究[J]. 岩石力学与工程学报，2015，34(9)：1 777–1 785. (ZHANG Bo，LI Shucai，YANG Xueying，et al. Mechanical property of rock-like material with intersecting multi-flaws under uniaxial compression[J]. Chinese Journal of Rock Mechanics and Engineering，2015，34(9)：1 777–1 785.(in Chinese))
[14] GEHLE C，KUTTER H K. Breakage and shear behaviour of intermittent rock joints[J]. International Journal of Rock Mechanics and Mining Sciences，2003，40(5)：687–700.
[15] 周 辉，孟凡震，张传庆，等. 不同位置和尺寸的裂隙对岩体破坏影响的试验研究[J]. 岩石力学与工程学报，2015，34(增1)：3 018–3 028.(ZHOU Hui，MENG Fanzhen，ZHANG Chuanqing，et al. Experimental study on effect of joints with different locations and sizes on rock failure[J]. Chinese Journal of Rock Mechanics and Engineering，2015，34(Supp.1)：3 018–3 028.(in Chinese))
[16] BOIS T，BOUISSOU S. Influence of tectonic fractures zones on gravitational rock slope failures：New insights from 2D physical modeling[J]. Journal of Geophysical Research. 2010，115(F3)：1–8.
[17] ZHANG K，CAO P，MENG J J，et al. Modeling the progressive failure of jointed rock slope using fracture mechanics and the strength reduction method[J]. Rock Mechanics and Rock Engineering，2015，48(2)：771–785.
[18] 王 飞，曹 平，曹日红，等. 平行节理相互作用对节理岩体的力学行为影响[J]. 中南大学学报：自然科学版，2018，49(10)：2 498–2 507.(WANG Fei，CAO Ping，CAO Rihong，et al. Influence of parallel joint interaction on mechanical behavior of jointed rock mass[J]. Journal of Central South University：Science and Technology，2018，49(10)：2 498–2 507.(in Chinese))
[19] RAO Q H，SUN Z Q，STEPHANSSON O，et al. Shear fracture(Mode II) of brittle rock[J]. International Journal of Rock Mechanics and Mining Sciences，2003，40(3)：355–375.
[20] 范文臣，曹 平，张 科. 不同压剪应力比作用下节理类岩石材料破坏模式的试验研究[J]. 中南大学学报：自然科学版，2015，46(3)：926–932.(FAN Wenchen，CAO Ping，ZHANG Ke. Experiment study on failure style of jointed rock-like material under different compressive-shear stress ratios[J]. Journal of Central South University：Science and Technology，2015，46(3)：926–932.(in Chinese))
[21] 张 科，陈宇龙，程赫明，等. 反倾角裂隙岩体压剪断裂及破碎特征研究[J]. 岩石力学与工程学报，2018，37(增1)：3 291–3 299. (ZHANG Ke，CHEN Yulong，CHENG Heming，et al. Investigation on compression-shear fracture and fragmentation characteristics of rock mass containing counter-inclined flaw[J]. Chinese Journal of Rock Mechanics and Engineering，2018，37(Supp.1)：3 291–3 299.(in Chinese))
[22] 朱泉企，李地元，李夕兵. 含预制椭圆形孔洞大理岩变形破坏力学特性试验研究[J]. 岩石力学与工程学报，2019，38(增1)：2 724–2 733.(ZHU Quanqi，LI Diyuan，LI Xibing. Experimental study on failure and mechanical characteristics of marble containing a prefabricated elliptical hole[J]. Chinese Journal of Rock Mechanics and Engineering，2019，38(Supp.1)：2 724–2 733.(in Chinese))
[23] 马永尚，陈卫忠，杨典森，等. 基于三维数字图像相关技术的脆性岩石破坏试验研究[J]. 岩土力学，2017，38(1)：117–123.(MA Yongshang，CHEN Weizhong，YANG Diansen，et al. Experimental study of brittle rock failure based on three-dimensional digital image correlation technique[J]. Rock and Soil Mechanics，2017，38(1)：117–123.(in Chinese))
[24] 袁 媛，潘鹏志，赵善坤，等. 基于数字图像相关法的含填充裂隙大理岩单轴压缩破坏过程研究[J]. 岩石力学与工程学报，2018，37(2)：339–351.(YUAN Yuan，PAN Pengzhi，ZHAO Shankun，et al. The failure process of marble with filled crack under uniaxial compression based on digital image correlation[J]. Chinese Journal of Rock Mechanics and Engineering，2018，37(2)：339–351.(in Chinese))
[25] 宋义敏，姜耀东，马少鹏，等. 岩石变形破坏全过程的变形场和能量演化研究[J]. 岩土力学，2012，33(5)：1 352–1 356.(SONG Yimin，JIANG Yaodong，MA Shaopeng，et al. Evolution of deformation fields and energy in whole process of rock failure[J]. Rock and Soil Mechanics，2012，33(5)：1 352–1 356.(in Chinese))
[26] 赵 程，田加深，松田浩，等. 单轴压缩下基于全局应变场分析的岩石裂纹扩展及其损伤演化特性研究[J]. 岩石力学与工程学报，2015，34(4)：763–769.(ZHAO Cheng，TIAN Jiashen，MATSUDA Hiroshi，et al. Crack propagation and damage of rock under uniaxial compression based on global strain field analysis[J]. Chinese Journal of Rock Mechanics and Engineering，2015，34(4)：763–769.(in Chinese))
[27] LI D Y，ZHU Q Q，ZHOU Z L，et al. Fracture analysis of marble specimens with a hole under uniaxial compression by digital image correlation[J]. Engineering Fracture Mechanics，2017，183：109–124.
[28] ZHOU X P，ZHANG J Z，QIAN Q H，et al. Experimental investigation of progressive cracking processes in granite under uniaxial loading using digital imaging and AE techniques[J]. Journal of Structural Geology，2019，126：129–145.
[29] 张梅英，袁建新，李廷芥，等. 单轴压缩过程中岩石变形破坏机制[J]. 岩石力学与工程学报，1998，17(1)：1–8.(ZHANG Meiying，YUAN Jianxin，LI Tingjie，et al. Mechanism of deformation and failure for rock in uniaxial compression test[J]. Chinese Journal of Rock Mechanics and Engineering，1998，17(1)：1–8.(in Chinese))
[30] 黄明利，唐春安，朱万成. 岩石单轴压缩下破坏失稳过程SEM即时研究[J]. 东北大学学报：自然科学版，1999，20(4)：426–429.(HUANG Mingli，TANG Chun?an，ZHU Wangcheng. Real-time SEM study on rock failure instability under uniaxial compression[J]. Journal of Northeastern University：Natural Science，1999，20(4)：426–429.(in Chinese))
[31] 潘 兵，谢惠民. 数字图像相关中基于位移场局部最小二乘拟合的全场应变测量[J]. 光学学报，2007，27(11)：1 980–1 986.(PAN Bing，XIE Huimin. Full-Field strain measurement based on least-squarefitting of local displacement for digital image correlation method[J]. Acta Optica Sinica，2007，27(11)：1 980–1 986.(in Chinese))
[32] BLABER J，ADAIR B，ANTONIOU A. Ncorr：Open-source 2D digital image correlation matlab software[J]. Experimental Mechanics，2015，55(6)：1 105–1 122.
[33] BOBET A. The initiation of secondary cracks in compression[J]. Engineering Fracture Mechanics，2000，66(2)：187–219.
[34] JEAGER J C，COOK N G W. 岩石力学基础[M]. 3版. 中国科学院工程力学研究所译. 北京：科学出版社，1981：329–338.(JEAGER J C，COOK N G W. Fundamentals of rock mechanics[M]. 3rd ed. Translated by Institute of Mechanics，Chinese Academy of Sciences. Beijing：Science Press，1981：329–338.(in Chinese))
[35] ZHOU T，CHEN J R，XIE H P，et al. Failure and mechanical behaviors of sandstone containing a pre-existing flaw under compressive-shear loads：Insight from a digital image correlation(DIC) analysis[J]. Rock Mechanics and Rock Engineering，2022，55：4 237–4 256.
[36] 徐芝纶. 弹性力学[M]. 5版. 北京：高等教育出版社，2016：115–128.(XU Zhilun. Elastic mechanic[M]. 5th ed. Beijing：Higher Education Press，2016：115–128.(in Chinese))
[37] 左建平，谢和平，周宏伟，等. 温度–拉应力共同作用下砂岩破坏的断口形貌[J]. 岩石力学与工程学报，2007，26(12)：2 444–2 457. (ZUO Jianping，XIE Heping，ZHOU Hongwei，et al. Fractography of sandstone failure under temperature-tensile stress coupling effects[J]. Chinese Journal of Rock Mechanics and Engineering，2007，26(12)：2 444–2 457.(in Chinese))
[38] 李先炜，兰勇瑞，邹俊兴. 岩石断口分析[J]. 中国矿业学院学报，1983，12(1)：18–24.(LI Xianwei，LAN Yongrui，ZOU Junxing. A study of rock fractures[J]. Journal of China University of Mining and Technology，1983，12(1)：18–24.(in Chinese))
[39] 谢和平，陈至达. 岩石断裂的微观机制分析[J]. 煤炭学报，1989，14(2)：57–67.(XIE Heping，CHEN Zhida. Analysis of rock fracture micro-mechanism[J]. Journal of China Coal Society，1989，14(2)：57–67.(in Chinese))
2023, Vol. 42 
