Empirical formula of shear strength for double structural plane based on joint roughness coefficient
FAN Xiang1，2，3，DENG Zhiying1，AN Honglei1，WU Rui1，REN Xianda1，DING Fan1
(1. School of Highway，Chang?an University，Xi?an，Shaanxi 710064，China；2. Hunan Province Key Laboratory of Safe Mining Techniques of Coal Mines，Hunan University of Science and Technology，Xiangtan，Hunan 411201，China；
3. CCCC First Highway Consultants Co. Ltd.，Xi?an，Shaanxi 710075，China)
Abstract：To reveal the shear strength difference of direct shear and bi-direct shear of structural plane and better evaluate the stability of layered rock mass，four Barton standard profile lines were selected to establish the structural plane models，and the rock-like samples containing one or two structural planes were made for shear tests. Based on the experimental results，the differences of peak shear strength( ) between single and double structural planes under three normal stresses( ) as well as the reasons for them were analyzed quantitatively. Based on the particle flow simulation results，the empirical formula of the peak shear strength for the double structural plane with the same JRC value was derived firstly. Then，the combined joint roughness coefficient ( ) was introduced to characterize the roughness of double structural plane with different JRC values. After the relevance between low roughness coefficient( )，high roughness coefficient( ) and was found，an empirical formula of the double structural plane with different JRC values considering the effect of and to peak shear strength was established. Eventually，an empirical formula of the peak shear strength for double structural plane with any combination of JRC values was established via a comprehensive analysis of the evolution of peak shear strength with the mixed joint roughness coefficient. During the process that the growth trend of -JRC curve increases with the increase of ，the peak shear strength of double structural plane increases with the sum of JRC value when is constant. Importantly，when the sum of JRC value is small，the peak shear strength of double structural plane with different JRC values is controlled by the side of lower JRC. However，the control effect decreases with the increase of the sum of JRC value，and thus the peak shear strength is gradually controlled by the side of higher JRC.
BARTON N，CHOUBEY V. The shear strength of rock joints in theory and practice[J]. Rock Mechanics and Rock Engineering，1977，10(1/2)：1-54.
[2]
BARTON N，BANDIS S. Review of predictive capabilities of JRC-JCS model in engineering practice[C]// Proceedings of the International Symposium on Rock Joints. Rotterdam：A. A. Balkema，1990：603-610.
[3]
WEI H，YI J. The relationship between characteristics and shear strength of structural planes and its effect on the stability of landslide[J]. Advanced Materials Research，2012，(430/432)：956-959.
[4]
衡 帅，杨春和，曾义金，等. 基于直剪试验的页岩强度各向异性研究[J]. 岩石力学与工程学报，2014，33(5)：874-883.(HENG Shuai，YANG Chunhe，ZENG Yijin，et al. Anisotropy of shear strength of shale based on direct shear test[J]. Chinese Journal of Rock Mechanics and Engineering，2014，33(5)：874-883.(in Chinese))
[5]
刘 伟，曾亚武，夏 磊，等. 正反向直剪下层状岩体强度和破坏特征模型试验[J]. 武汉大学学报：工学版，2019，52(7)：600-609. (LIU Wei，ZENG Yawu，XIA Lei，et al. Model tests for strength and failure characteristics of forward and reverse shear rock masses[J]. Engineering Journal of Wuhan University，2019，52(7)：600-609.(in Chinese))
XU Bing，ZHOU Xiaohan，et al. Investigation on the macro-meso shear mechanical properties of soft-hard interbedded rock discontinuity[J]. Journal of China Coal Society，2021，46(9)：2 895-2 909.(in Chinese))
[7]
尹立明，张培森. 双结构面对岩体强度影响的模拟分析[J]. 采矿与安全工程学报，2010，27(4)：600-603.(YIN Liming，ZHANG Peisen. Simulation analysis of rock mass strength affected by dual structural plane[J]. Journal of Mining and Safety Engineering，2010，27(4)：600-603.(in Chinese))
[8]
LI H H. Mechanical responses of rock joints with regular asperities under various shear rates investigated by double shear test[J]. Journal of Testing and Evaluation，2017，45(2)：470-483.
[9]
LIU X G，ZHU W C，YU Q L，et al. Estimation of the joint roughness coefficient of rock joints by consideration of two-order asperity and its application in double-joint shear tests[J]. Engineering Geology，2017，220：243-255.
[10]
刘溪鸽，朱万成，周靖人，等. 双粗糙结构面剪切试验与数值模拟研究[J]. 岩石力学与工程学报，2017，36(增2)：3 831-3 840.(LIU Xige，ZHU Wancheng，ZHOU Jingren，et al. Direct shear tests and numerical simulation of double rough joints[J]. Chinese Journal of Rock Mechanics and Engineering，2017，36(Supp.2)：3 831-3 840.(in Chinese))
[11]
唐志成，黄润秋，张建明，等. 含坡度均方根的节理峰值剪切强度经验公式[J]. 岩土力学，2015，36(12)：3 433-3 438.(TANG Zhicheng，HUANG Runqiu，ZHANG Jianming，et al. Empirical peak shear strength criterion for rock joints based on slope root-mean- square[J]. Rock and Soil Mechanics，2015，36(12)：3 433-3 438.(in Chinese))
[12]
DONG H Y，GUO B H，LI Y Z，et al. Empirical Formula of shear strength of rock fractures based on 3D morphology parameters[J]. Geotechnical and Geological Engineering，2017，35(3)：1 169-1 183.
[13]
程 坦，郭保华，孙杰豪，等. 非规则岩石节理峰值剪切试验与强度经验公式研究[J]. 岩石力学与工程学报，2022，41(1)：93-105.(CHENG Tan，GUO Baohua，SUN Jiehao，et al. Study on peak shear test and strength empirical formula of irregular rock joints[J]. Chinese Journal of Rock Mechanics and Engineering，2022，41(1)：93-105.(in Chinese))
[14]
石 崇. 颗粒流(PFC5.0)数值模拟技术及应用[M]. 北京：中国建筑工业出版社，2018：262-278.(SHI Chong. Numerical simulation technology and application with Particle Flow Code(PFC5.0)[M]. Beijing：China Architecture and Building Press，2018：262-278.(in Chinese))
[15]
范 祥，邓志颖，崔志猛，等. 一种新的软-硬节理峰值剪切强度模型[J]. 岩土力学，2021，42(7)：1 861-1 870.(FAN Xiang，DENG Zhiying，CUI Zhimeng，et al. A new peak shear strength model for soft-hard joint[J]. Rock and Soil Mechanics，2021，42(7)：1 861- 1 870.(in Chinese))
[16]
宋磊博，江 权，李元辉，等. 软-硬自然节理的改进JRC-JCS剪切强度公式[J]. 岩土力学，2017，38(10)：2 789-2 798.(SONG Leibo，JIANG Quan，LI Yuanhui，et al. Improved JRC-JCS shear strength formula for soft-hard natural joints[J]. Rock and Soil Mechanics，2017，38(10)：2 789-2 798.(in Chinese))
2023, Vol. 42 
