作者中心
专家审稿
编委审稿
主编审稿
MICROSTRUCTURE FRACTURE CHARACTERISTICS AND DILATANCY EFFECT OF ROCK BRIDGE UNDER DIRECT SHEAR TESTS
-
摘要: 节理岩体的剪切贯通机制影响着边坡的稳定性。为揭示锁固段型非贯通节理岩体在不同连通率和法向应力下的破坏特征，在室内直剪试验中结合高速摄影与AE特征参数分析其剪切全过程及剪胀效应。结果表明：节理岩体直剪试验中，法向应力的增大及节理连通率的下降会致使峰值剪切应力及峰值剪切位移增大；节理连通率与法向应力对其破坏特征具显著影响，表现为节理连通率较高且法向应力较小时呈直接剪断的特性，节理连通率降低后呈拉剪复合破坏，出现剪胀现象，而法向应力的增大使得剪胀效应呈波动现象；AE特征与岩桥贯通过程一致，事件数峰值随节理连通率的降低及法向应力的增大而增大且位于峰后。试验得到的岩桥细观破坏特征与剪胀效应对研究锁固段型岩质边坡的贯通破坏机制具指导意义。Abstract: The jointed rock masses with incomplete end joints and coalescence mechanisms of rock slopes are often encountered in engineering construction. They are complex. In order to reveal the relationship between the failure characteristics and dilatancy effect of end rock bridge under different joint connectivity rates and normal stresses, we carry out the direct shear test of the rock bridge to explore the failure process of the front locked section slope. The whole process of shear stress change is analyzed by high-speed photography and AE characteristic parameters. After test, we find that the shear failure process of the end direct shear specimens can be divided into five stages: crack compaction, stable crack propagation, progressive propagation, strain softening and residual strength stage. The decrease of joint connectivity rate and the increase of normal stress lead to the increase of peak shear displacement and peak shear stress. The joint connectivity rate and normal stress have significant influence on the failure characteristics of rock mass. When the joint connectivity rate is high and the normal stress is small, the cracks propagate in a straight line. With the decrease of the length of joint connectivity rate, the phenomenon of shear dilatancy occurs, and the cracks become irregular curves. Meanwhile, the increase of normal stress causes the dilatancy phenomenon to fluctuate. The AE characteristics are consistent with the rock bridge crossing process. The peak number of AE events increases with the decrease of the joint connectivity rate and the increase of normal stress. The tests demonstrate that the microscopic failure characteristics and dilatancy effect of rock bridge are extremely significant for studying the failure mechanism of the locked section slope as a guide.
-
Key words:
- Rock mechanics /
- Direct shear /
- Joint rock /
- Dilatancy effect
-
图 2 加载系统、AE以及高速摄像机布置
Figure 2. Loading system, digital AE system and high speed camera layout
图 4 直剪全过程剪切应力-剪切位移曲线
a.法向应力0.70 MPa，节理连通率50%；b.节理连通率50%；c.节理连通率60%；d.节理连通率70%；e.节理连通率80%
Figure 4. Curve of shear stress-shear displacement in the whole process of direct shear
图 6 法向应力0.85 MPa剪切应力-剪位移曲线
Figure 6. Shear stress-shear displacement curve under normal stress 0.85 MPa
图 8 切向位移-法向位移曲线
a.节理连通率60%；b.节理连通率70%；c.节理连通率80%
Figure 8. Tangential displacement-normal displacement curve
图 9 节理岩体直剪试验加载及端部受力示意图
Figure 9. Diagram of loading and end force in direct shear test of jointed rock mass
表 1 剪胀阶段割线斜率
Table 1. Secant slope in dilatancy stage
节理连通率
/%法向应力/MPa 0.7 0.85 1 1.15 1.3 60 0.333 0.341 0.312 0.266 0.355 70 0.331 0.110 0.154 0.109 0.073 80 0 0 0.133 0 0 
下载: 导出CSV
表 2 不同节理连通率下的3种剪切破坏模式
Table 2. Three shear failure modes with different joint connectivity
破坏方式 破坏过程及特征 示意图 破坏照片 直接剪断 试样破坏的初裂纹很小，且与剪切面小角度相交，甚至无初裂纹。岩桥直接剪断破坏，剪胀效应不明显，岩桥破坏面较平直，粗糙度较小 
压致拉裂
后剪断在未施加剪切位移之前，试样就出现有压制拉裂，裂纹由岩桥端部发育，之后岩桥剪断 
剪胀剪断 破坏面近于弧形，在剪切过程中拉裂纹的连通会导致掉快现象，剪胀效应也变得更为明显 
下载: 导出CSV
表 3 特征曲线
Table 3. Acoustic emission characteristic curve
-
Bai S W, Ren W Z, Feng D X, et al. 1999. Research on the strength behaviour of rock containing coplanar close intermittent joints by direct test[J]. Rock and Soil Mechanics, 20(2): 10-16. Chen H R, Qin S Q, Xue L, et al. 2019. Modes of mechanical action between locked segments[J]. Journal of Engineering Geology, 27(1): 1-13. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=gcdzxb201901001 Du J C, Chen Z Y. 2002. A Simplified discontinuity propagation model and its application in mechanics of rock mass[J]. Chinese Journal of Geotechnical Engineering, 24(4): 421-426. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=ytgcxb200204003 Huang D, Huang R Q, Lei P. 2014. Shear deformation and strength of through-going saw-tooth rock discontinuity[J]. Journal of China Coalsociety, 39(7): 1229-1237. http://d.old.wanfangdata.com.cn/Periodical/mtxb201407006 Lajtai E Z. 1969a. Shear strength of weakness planes in rock[J]. International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, 6(5): 499-515. Lajtai E Z. 1969b. Strength of discontinuous rocks in direct shear[J]. Géotechnique, 19(2): 218-233. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=df74765c0e96986935a86d72300950a2 Li X F, Li H B, Xia X, et al. 2016. Numerical simulation of mechanical characteristics of jointed rock in direct shear test[J]. Rock and Soil Mechanics, 37(2): 583-591. http://d.old.wanfangdata.com.cn/Periodical/ytlx201602032 Liu S Q, Ma F S, Zhao H J, et al. 2018. RJM based numerical study of strength and failure modes of rockmass with discontinuous joints[J]. Journal of Engineering Geology, 26(5): 1342-1350. http://d.old.wanfangdata.com.cn/Periodical/gcdzxb201805030 Liu Y M, Xia C C. 2010a. Research on rock mass containing discontinuous joints by direct shear test based on weakening mechanism of rock bridge mechanical properties[J]. Chinese Journal of Rock Mechanics and Engineering, 29(7): 1467-1472. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=yslxygcxb201007022 Liu Y M, Xia C C. 2010b. Weakening mechanism of mechanical behaviors and failure models of rock mass containing discontinuous joints under direct shear condition[J]. Rock and Soil Mechanics, 31(3): 695-701. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=ytlx201003005 Liu Y M. 2007. Study on failure models and strength of rockmass containing discontinuous joints in direct shear[D]. Shanghai: Tongji University. Savilabti T, Nordlund E, Stephansson O. 1990. Shearbox testing and modeling of joint bridge[C]//Proc Int Symp Rock Joints. Norway: [s.n.]: 295-300. Wong R, Leung W, Wang S. 2001. Shear strength studies on rock-like models containing arrayed open joints[J]. Rock Mechanics in the National Interest, 1(2): 843-849. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=CC027298253 Xu W Z, Lin H, Cao R H. 2018. Simulation and macro-mesoscopic parameter analysis for direct shear of filled rough joints[J]. Journal of Southwest Jiaotong University, 53(3): 548-557. http://d.old.wanfangdata.com.cn/Periodical/xnjtdxxb201803016 Xu Y F. 2018. PFC2D simulation of rockfill shear strength based on particle fragmentation[J]. Journal of Engineering Geology, 26(6): 1409-1414. http://d.old.wanfangdata.com.cn/Periodical/gcdzxb201806001 Zhong B B, Zhang Y B, Li H. 2014. Study of mechanisms of crack propagation of rock based on RFPA2D[J]. Journal of Wuhan University of Technology, 36(2): 82-88. http://d.old.wanfangdata.com.cn/Periodical/whgydxxb201402016 Zhu W S, Li S C, Chen W Z. 2002. Failure mechanism, anchorage effect and engineering application of jointed rock mass[M]. Beijing: Science Press. Zhu W S, Liang Z Y, Feng G B, et al. 1994. Physical simulation and strength prediction analysis of jointed rock mass[C]//Ge Xiulin. Application of computer methods in rock mechanics and engineering. Wuhan: Wuhan Surveying and Mapping Science and Technology Human Science Press. Zhu W S, Chen W Z, Shen J. 1998. Simulation experiment and fracture mechanism study on propagation of echelon pattern cracks[J]. Acta Mechanica Solida Sinica, 19(4): 355-360. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=QK199800141602 白世伟, 任伟中, 丰定祥, 等. 1999.共同闭合断续节理岩体强度特性直剪试验研究[J].岩土力学, 20(2): 10-16. http://www.cqvip.com/qk/94551X/199902/3579137.html 陈竑然, 秦四清, 薛雷, 等. 2019.锁固段之间的力学作用模式[J].工程地质学报, 27(1): 1-13. doi: 10.13544/j.cnki.jeg.2019-011 杜景灿, 陈祖煜. 2002.岩桥破坏的简化模型及在节理岩体中模拟网络中的应用[J].岩土工程学报, 24(4): 421-426. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=ytgcxb200204003 黄达, 黄润秋, 雷鹏. 2014.贯通型锯齿状岩体结构面剪切变形及强度特征[J].煤炭学报, 39(7): 1229-1237. http://d.old.wanfangdata.com.cn/Periodical/mtxb201407006 李晓锋, 李海波, 夏祥, 等. 2016.类节理岩石直剪试验力学特性的数值模拟研究[J].岩土力学, 37(2): 583-591. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=ytlx201602032 刘帅奇, 马凤山, 赵海军, 等. 2018.基于RJM断续节理岩体强度与破坏特征的数值模拟研究[J].工程地质学报, 26(5): 1342-1350. doi: 10.13544/j.cnki.jeg.2018250 刘远明, 夏才初. 2010a.基于岩桥力学性质弱化机制的非贯通节理岩体直剪试验研究[J].岩石力学与工程学报, 29(7): 1467-1472. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=yslxygcxb201007022 刘远明, 夏才初. 2010b.直剪条件下非贯通节理岩体岩桥力学性质弱化机制及贯通模型初步研究[J].岩土力学, 31(3): 695-701. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=ytlx201003005 刘远明. 2007.基于直剪试验的非贯通节理岩体扩展贯通研究[D].上海: 同济大学. http://www.wanfangdata.com.cn/details/detail.do?_type=degree&id=Y1228226 徐永福. 2018.基于颗粒破碎的粗粒土剪切强度的模拟分析[J].工程地质学报, 26(6): 1409-1414. doi: 10.13544/j.cnki.jeg.2017-432 许万忠, 林杭, 曹日红. 2018.充填粗糙节理直剪数值模拟宏细观分析[J].西南交通大学学报, 53(3): 548-557. http://d.old.wanfangdata.com.cn/Periodical/xnjtdxxb201803016 钟波波, 张永彬, 李宏. 2014.基于RFPA2D的岩石裂纹扩展模式的研究[J].武汉理工大学学报, 36(2): 82-88. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=whgydxxb201402016 朱维申, 陈卫忠, 申晋. 1998.雁形裂纹扩展的模型试验及断裂力学机制研究[J].固体力学学报, 19(4): 355-360. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=QK199800141602 朱维申, 李术才, 陈卫忠. 2002.节理岩体破坏机理和锚固效应及工程应用[M].北京:科学出版社. 朱维申, 梁作元, 冯光北, 等. 1994.节理岩体强度特性的物理模拟及其强度预测分析[C]//葛修润: 计算机方法在岩石力学及工程中的应用国际学术讨论文集.武汉: 武汉测绘科技人学出版社. -
点击查看大图
图(11) / 表(3)
计量
- 文章访问数: 2867
- HTML全文浏览量: 500
- PDF下载量: 105
- 被引次数: 0
