|
|
|
| MESOSCOPIC CRACKING AND EXPANSION OF DOUBLE SHEARED SANDSTONE UNDER COMPRESSIVE-SHEAR STRESS |
| XU Jiang1，2，LIU Jing1，2，CHENG Lichao1，2，FENG Dan1，2，LIU Yixin1，2 |
(1. State Key Laboratory of Coal Mine Disaster Dynamics and Control，Chongqing University，Chongqing 400044，China；
2. State and Local Joint Engineering Laboratory of Methane Drainage in Complex Coal Gas Seam，Chongqing University，Chongqing 400044，China) |
|
|
|
|
Abstract The mesoscopic test device developed studying the crack process of coal and rock under double shear was used in the shear test at different stress conditions. The acoustic emission and image processing techniques were employed to measure the mesoscopic cracking propagation process and the mesoscopic cracking extension space distribution. For the double shear test under compression and shearing，the damage of the surface of the specimen is not visible in most of the period of loading process and the surface cracks occur just before the shear stresses reach the peak value. When the shear stresses are nearly reaching the peak，the rate of Hit has a sharp increase indicating that there are already cracks inside the sandstone，while on the surface there are no cracks，and the tiny cracks can only be seen after a period of time. Presumably，the cracks developed from inside to outside. After the macroscopic damage，the left and right sides of cracks show a splayed or trapezoidal distribution. Because the internal shear failure of rock mass is mainly caused by the vertical shear force and the sand grains possess the different geometric and physical properties，the main crack along the shear plane extended irregularly. Cracks always occur in the edges of mineral particles like quartz，feldspar etc which are the weakest links of sandstone. As the shear stress level increases，the cracks will cross over the mineral particles and form transgranular fractures. This phenomenon is often seen in quartz grains because of its specific relevant microstructure features.
|
|
Received: 02 July 2013
|
|
|
|
| [1] 蔡美峰，何满潮，刘东燕. 岩石力学与工程[M]. 北京：科学出版社，2002：12–17.(CAI Meifeng，HE Manchao，LIU Dongyan. Rock mechanics and engineering[M]. Beijing：Science Press，2002：12–17. (in Chinese))
[2] 刘冬梅，龚永胜，谢锦平，等. 压剪应力作用下岩石变形破裂全程动态监测研究[J]. 南方冶金学院学报，2003，24(5)：69–72.(LIU Dongmei，GONG Yongsheng，XIE Jinping，et al. Wholly dynamic testing study of rock deformation and fracture under compressive and shearing stress[J]. Journal of Southern Institute of Metallurgy，2003，24(5)：69–72.(in Chinese))
[3] 刘冬梅，蔡美峰，周玉斌，等. 岩石裂纹扩展过程的动态监测研究[J]. 岩石力学与工程学报，2006，25(3)：467–472.(LIU Dongmei，CAI Meifeng，ZHOU Yubin，et al. Dynamic monitoring on developing process of Rock cracks[J]. Chinese Journal of Rock Mechanics and Engineering，2006，25(3)：467–472.(in Chinese))
[4] 刘冬梅，蔡美峰，周玉斌. 岩石细观损伤演化与宏观变形响应关联研究[J]. 中国钨业，2006，21(4)：16–19.(LIU Dongmei，CAI Meifeng，ZHOU Yubin. Study on the relationship between mesodamage development and macro deformation of rock under uniaxial compression[J]. China Tungsten Industry，2006，21(4)：16–19.(in Chinese))
[5] 刘冬梅，谢锦平，周玉斌，等. 岩石压剪耦合破坏过程的实时监测研究[J]. 岩石力学与工程学报，2004，23(10)：1 616–1 620.(LIU Dongmei，XIE Jinping，ZHOU Yubin，et al. Real-time testing study of rock fracture under coupled compression and shear[J]. Chinese Journal of Rock Mechanics and Engineering，2004，23(10)：1 616–1 620. (in Chinese))
[6] LAJTAI E Z. Strength of discontinuous rocks in direct shear[J]. Geotechnique，1969，19(2)：28–33.
[7] LAJTAI E Z. Shear strength of weakness planes in rock[J]. International Journal of Rock Mechanics and Mining Sciences，1969，6(5)：499–515.
[8] 蒋 宇，葛修润，任建喜. 岩石疲劳破坏过程中的变形规律及声发射特性[J]. 岩石力学与工程学报，2004，23(11)：1 810–1 814. (JIANG Yu，GE Xiurun，REN Jianxi. Deformation rules and acoustic emission characteristics of racks in process of fatigue failure[J]. Chinese Journal of Rock Mechanics and Engineering，2004，23(11)：1 810–1 814.(in Chinese))
[9] 葛修润，任建喜，蒲毅彬，等. 岩石细观损伤扩展规律的CT实时试验[J]. 中国科学：E辑，2000，30(2)：104–111.(GE Xiurun，REN Jianxi，PU Yibin，et al. Real-time CT test on the meso-damage development law of rock[J]. Science in China：Series E，2000，30(2)：104–111.(in Chinese))
[10] 杨 萌，黄承逵. 钢纤维高强混凝土轴拉性能试验研究[J]. 土木工程学报，2006，39(3)：55–61.(YANG Meng，HUANG Chengkui. Study on stress-strain curve of high strength steel fiber reinforced concrete under uniaxial tension[J]. China Civil Engineering Journal，2006，39(3)：55–61.(in Chinese))
[11] 吴立新，刘善军，吴育华，等. 遥感–岩石力学(II)——断层双剪黏滑的热红外辐射规律及其构造地震前兆意义[J]. 岩石力学与工程学报，2004，23(2)：192–198.(WU Lixin，LIU Shanjun，WU Yunhua，et al. Remote sensing-rock mechanics(II)：laws of thermalinfrared radiation from viscosity-sliding of bi-sheared faults and its meanings for tectonic earthquake omens[J]. Chinese Journal of Rock Mechanics and Engineering，2004，23(2)：192–198.(in Chinese))
[12] 许 江，陆丽丰，杨红伟，等. 剪切荷载作用下砂岩细观开裂扩展演化特征研究[J]. 岩石力学与工程学报，2011，30(5)：944–950.(XU Jiang，LU Lifeng，YANG Hongwei，et al. Study of evolution law of microfracturing progress of sandstone under shear loading[J]. Chinese Journal of Rock Mechanics and Engineering，2011，30(5)：944–950.(in Chinese))
[13] 李银平，蒋卫东，刘 江，等. 湖北云应盐矿深部层状盐岩之间试验研究[J]. 岩石力学与工程学报，2007，26(9)：1 767–1 772.(LI Yinping，JIANG Weidong，LIU Jiang，et al. Direct shear tests forlayered salt rocks of Yunying salt mine in Hubei Province[J]. Chinese Journal of Rock Mechanics and Engineering，2007，26(9)：1 767–1 772.(in Chinese))
[14] 李 炼，徐 钺，李启光，等. 花岗岩渐进破坏过程的微观研究[J]. 岩石力学与工程学报，2002，21(7)：940–947.(LI Lian，TSUI Y，LEE P K K，et al. Progressive cracking of granite plate under uniaxial compression[J]. Chinese Journal of Rock Mechanics and Engineering，2002，21(7)：940–947.(in Chinese))
[15] 许 江，程立朝，谭皓月，等. 原生裂纹对煤岩剪切破坏宏细观演化规律的影响研究[J]. 岩石力学与工程学报，2013，32(1)：33–40.(XU Jiang，CHENG Lichao，TAN Haoyue，et al. Effects of original cracks on micro-meso evolution law of coal shear failure[J]. Chinese Journal of Rock Mechanics and Engineering，2013，32(1)：33–40.(in Chinese))
[16] 刘东燕. 断续节理岩体的压剪断裂及其强度特性研究[博士学位论文][D]. 重庆：重庆建筑大学，1993.(LIU Dongyan. Research on mixed mode fracture in rock and strength properties of rock mass with intermittent joints[Ph. D. Thesis][D]. Chongqing：Chongqing Jianzhu University，1993.(in Chinese))
[17] 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)) |
|
|
|
2014, Vol. 33 
