Experimental study on mechanism for fracture network initiation under complex stress conditions
LIU Xuewei1，LIU Quansheng1，2，LIU Jianping1，WEI Lai1
(1. State Key Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics，Chinese Academy of Sciences，Wuhan，Hubei 430071，China；2. Key Laboratory of Safety for Geotechnical and Structural Engineering of Hubei Province，Wuhan University，Wuhan，Hubei 430072，China)
Abstract：As one of the most common object in rock engineering，the fractures in the rock mass may appear initiation and propagation under the engineering disturbances. Fracture initiation and propagation will change the deformation and strength characteristics of rock mass obviously. Therefore，a series of uniaxial and biaxial compression tests are carried out for the fractured specimens through RMT–150C and lateral pressure-adding equipment. Combined with the characters analysis of fracture propagation path，failure modes，acoustic emission (AE) energy and the positions of AE events under different loading conditions，the mechanism of fracture propagation is researched. With the increase of lateral pressure，the ductility of stress-strain curves increases. The newly formed cracks propagate from the initial fracture tips under the whole conditions，while the propagation path changed hugely under the biaxial compression condition. The positions of AE events during the loading process match well with the macroscopical fracture propagation path. The ratios of AE events before fracture initiation and the whole loading process for the typical specimens are all above 80%，which proves that the fracture initiation and propagation is the result of microcracks development and damage accumulation in the specimen. The results are significant for simulating unstable process of engineering rock mass more effectively.
张 波，李术才，杨学英，等. 含交叉裂隙节理岩体单轴压缩破坏机制研究[J]. 岩土力学，2014，35(7)：1 863-1 870.(ZHANG Bo，LI Shucai，YANG Xueying，et al. Uniaxial compression failure mechanism of jointed rock mass with cross-cracks[J]. Rock and Soil Mechanics，2014，35(7)：1 863-1 870.(in Chinese))
[2]
SATO A，HIRAKAWA Y，SUGAWARA K. Mixed mode crack propagation of homogenized cracks by the two-dimensional DDM analysis[J]. Construction and Building Materials，2001，15(5/6)：247-261.
[3]
黄明利，冯夏庭，王水林. 多裂纹在不同岩石介质中的扩展贯通机制分析[J]. 岩土力学，2002，23(2)：142-146.(HUANGMingli，FENG Xiating，WANG Shuilin. Numerical simulation of propagation and coalescenceprocesses of multi-crack in different rock media[J]. Rock and Soil Mechanics，2002，23(2)：142-146.(in Chinese))
[4]
梁正召，李连崇，唐世斌，等. 岩石三维表面裂纹扩展机理数值模拟研究[J]. 岩土工程学报，2011，33(10)：1 615-1 622.(LIANG Zhengzhao，LI Lianchong，TANG Shibin，et al. 3D numerical simulation of growth of surface crack of rock specimens[J]. Chinese Journal of Geotechnical Engineering，2011，33(10)：1 615-1 622.(in Chinese))
[5]
LIANG Z Z，XING H，WANG S Y，et al. A three-dimensional numerical investigation of the fracture of rock specimens containing a pre-existing surface flaw[J]. Computers and Geotechnics，2012，45：19-33.
[6]
蒲成志，曹 平，张春阳，等. 双向压缩条件下闭合裂隙岩体断裂破坏机制及渗透压环境判定准则[J]. 岩土力学，2015，36(1)：56-60.(PU Chengzhi，CAO Ping，ZHANG Chunyang，et al. Fracture failure mechanism of rock with closed crack and judging criterion of seepage pressure under biaxial compression[J]. Rock and Soil Mechanics，2015，36(1)：56-60.(in Chinese))
[7]
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))
[8]
赵延林，彭青阳，万 文，等. 高水压下岩体裂纹扩展的渗流-断裂耦合机制与数值实现[J]. 岩土力学，2014，35(2)：556-564.(ZHAO Yanlin，PENG Qingyang，WAN Wen，et al.Seepage-fracture coupling mechanism of rock massescracking propagation under high hydraulic pressure andnumerical verification[J]. Rock and Soil Mechanics，2014，35(2)：556-564.(in Chinese))
[9]
肖桃李，李新平，郭运华. 三轴压缩条件下单裂隙岩石的破坏特性研究[J]. 岩土力学，2012，33(11)：3251-3256.(XIAO Taoli，LI Xinping，GUO Yunhua. Experimental study of failure characteristic of single jointed rock mass under triaxial compression tests[J]. Rock and Soil Mechanics，2012，33(11)：3251-3256.(in Chinese))
[10]
任建喜，冯晓光，刘 慧. 三轴压缩单一裂隙砂岩细观损伤破坏特性CT分析[J]. 西安科技大学学报，2009，29(3)：300-304.(REN Jianxi，FENG Xiaoguang，LIU Hui. CT testing on meso-damage propagation mechanism of cracked sandstone sample under triaxial compression loading[J]. Journal of Xi′an University of Science and Technology，2009，29(3)：300-304.(in Chinese))
[11]
黄明利，黄凯珠. 三维表面裂纹相互作用扩展贯通机制试验研究[J]. 岩石力学与工程学报，2007，26(9)：1794-1799.(HUANG Mingli，WONG R H C. Experimental study on propagation and coalescence mechanisms of 3D surface cracks[J]. Chinese Journal of Rock Mechanics and Engineering，2007，26(9)：1 794-1 799.(in Chinese))
[12]
刘彩平，鞠 杨，段庆全. 岩石材料内部特征尺度对裂纹扩展机制的影响[J]. 岩土力学，2010，31(增1)：91-95.(LIU Caiping，JU Yang，DUAN Qingquan. Influence of internal characteristic length scale on dynamic crack propagating mechanism in rock materials[J]. Rock and Soil Mechanics，2010，31(Supp.1)：91-95.(in Chinese))
[13]
吕森鹏，陈卫忠，贾善坡，等. 脆性岩石破坏试验研究[J]. 岩石力学与工程学报，2009，28(增1)：2 823-2 829.(LUSenpeng，CHEN Weizhong，JIA Shanpo，et al. Experimental study on brittle rock failure[J]. Chinese Journal of Rock Mechanics and Engineering， 2009，28(Supp.1)：2 823-2 829.(in Chinese))
[14]
杨永明，鞠 杨，陈佳亮，等. 三轴应力下致密砂岩的裂纹发育特征与能量机制[J]. 岩石力学与工程学报，2014，33(4)：691-698. (YANG Yongming，JU Yang，CHEN Jialiang，et al. Cracks development features and energy mechanism of dense sandstone subjected to triaxial stress[J]. Chinese Journal of Rock Mechanics and Engineering，2014，33(4)：691-698.(in Chinese))
[15]
戴永浩，陈卫忠，王者超，等. 非饱和板岩裂隙扩展机制CT试验研究[J]. 岩石力学与工程学报，2006，25(12)：2 537-2 545.(DAI Yonghao，CHEN Weizhong，WANG Zhechao，et al. Study on crack propagation of unsaturated slate by CTtests[J]. Chinese Journal of Rock Mechanics and Engineering，2006，25(12)：2 537-2 545.(in Chinese))
[16]
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)：5652- 5657.(LIN Peng，WONGR H C，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))
[17]
WONG R H C，CHAU K T，TANG C A，et al. Analysis of crack coalescence in rock-like materials containing three flaws—part I：experimental approach[J]. International Journal of Rock Mechanics and Mining Sciences，2001，38(7)：909-924.
2016, Vol. 35 
