|
|
|
| Combined test system for size effect of rock joint shear strength and its primary application research |
| DU Shigui1，LYU Yuanjun1，LUO Zhanyou2，HUANG Man3#br# |
| (1. Institute of Rock Mechanics，Ningbo University，Ningbo，Zhejiang 315211，China；2. Institute of Geotechnical Engineering，Zhejiang University of Science and Technology，Hangzhou，Zhejiang 310023，China；3. Department of Civil Engineering，Shaoxing University，Shaoxing，Zhejiang 312000，China) |
|
|
|
|
Abstract The size effect of rock joint shear strength is a basic research issue in the field of rock mechanics and engineering geology. Due to the lack of mature direct shear test equipment on series size specimens at home and abroad，the research process on shear strength size effect of rock joints is slow. In this paper，a shear strength size effect direct shear combined test system of rock joints is developed，and the key technologies and methods are put forward such as fast conversion of multi-scale jointed specimens，classification of load measurement and control system，equivalence check of overlapping specimens，dynamic detection in testing process and shear loss measurement of structural planes，providing a basis experimental support platform for investigating the size effect of rock joint shear strength and other key scientific issues. The preliminary application results of the developed test system are demonstrated by two-level direct shear apparatus. It is shown that the test system can solve the problem of automatic transformation of specimens in the range of 100 times of the rock joint size from 10 cm×10 cm to 100 cm×100 cm，involving the process of transporting，positioning，loading and resetting of multi-scale specimens. The test system can also solve the problem of accuracy and stability of the measurement control system in the range of 500 times of the load from 2 kN to 1 000 kN. The accuracy level of the test system reaches 0.5 through the identification of a testing organization. The shear strength test results of overlapped specimens of 30 cm×30 cm and 40 cm×40 cm in two-level direct shear apparatus are compared，which shows that the convergence of the two sizes of samples is good. For the specimens with the same structural plane sizes under different loads，the peak values of the tangential load are related to the applied normal loads. For the specimens with different structural plane sizes under the same load，however，the ratio of the tangential load peak value to the normal load has a stable trend，except for a slight fluctuation in a certain size range of the structural plane.
|
|
|
|
|
|
[1] BIENIAWSKI Z T. Determining rock mass deformability：experience from case histories[J]. International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts，1978，15(5)：237–247.
[2] HEUZE F E. Scale effects in the determination of rock mass strength and deformability[J]. Rock Mechanics and Rock Engineering，1980，12(3)：167–192.
[3] PINTO A，CUNHA D A. Scale effects in rock masses[M]. Boca Raton：CRC Press，2020：77–103.
[4] 靖洪文，苏海健，杨大林，等. 损伤岩样强度衰减规律及其尺寸效应研究[J]. 岩石力学与工程学报，2012，31(3)：543–549.(JING Hongwen，SU Haijian，YANG Dalin，et al. Study of strength degradation law of damaged rock sample and its size effect[J]. Chinese Journal of Rock Mechanics and Engineering，2012，31(3)：543–549.(in Chinese))
[5] 周火明，盛 谦，邬爱清. 三峡工程永久船闸边坡岩体宏观力学参数的尺寸效应研究[J]. 岩石力学与工程学报，2001，20(5)：661–664.(ZHOU Huoming，SHENG Qian，WU Aiqing. Size effect analysis on macro-mecheanics parameters for the rock masses of the tgp shiplock slope[J]. Chinese Journal of Rock Mechanics and Engineering，2001，20(5)：661–664.(in Chinese))
[6] BARTON N，CHOUBEY V. The shear strength of rock joints in theory and practice[J]. Rock Mechanics，1997，(10)：1–54.
[7] BANDIS S，LUMSDEN A C，BARTON N. Experimental studies of scales effects on the shear behaviour of rock joints[J]. International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts，1981，18(1)：1–21.
[8] CASTELLI M，SAVIA S，ZANINETI A. Experimental evaluation of scale effect on the mechanical behavior of rock joints[C]// Proceedings of International Eurock Symposium. Espoo Finland：[s. n.]，2001：205–210.
[9] BARLA G，BARLA M，MARTINOTTI M E. Development of a new direct shear testing apparatus[J]. Rock Mechanics and Rock Engineering，2010，43：117–122.
[10] JIANG Y，XIAO J，TANABASHI Y，et al. Development of an automated servo-controlled direct shear apparatus applying a constant normal stiffness condition[J]. International Journal of Rock Mechanics and Mining Sciences，2004，41(2)：275–286.
[11] KIM D Y，CHUN B S，YANG J S. Development of a direct shear apparatus with rock joints and its verification tests[J]. Geotechnical Testing Journal，2006，29(5)：365–373.
[12] SHRIVASTAVA A K，RAO K S. Development of a large-scale direct shear testing machine for unfilled and in filled rock joints under constant normal stiffness conditions[J]. Geotechnical Testing Journal，2013，36 (5)：671–679.
[13] RAO K S，SHRIVASTAVA A K. Development of an automated large scale direct shear testing machine for rock[C]// Indian Geotechnical Congress 2009. Guntur，India：Indian Geotechnical Society，2009：238–244.
[14] 闵 弘，刘小丽，魏进兵，等. 大型现场室内两用直剪仪研制(I)：结构设计[J]. 岩土力学，2006，27(1)：164–168.(MIN Hong，LIU Xiaoli，WEI Jinbing，et al. A new large direct shear apparatus for field and laboratory test(I)：configuration[J]. Rock and Soil Mechanics，2006，27(1)：164–168.(in Chinese))
[15] 刘小丽，罗锦添，闵 弘，等 大型现场室内两用直剪仪研制(II)：试验测试[J]. 岩土力学，2006，27(2)：336–340.(LIU Xiaoli，LAW K T，MIN Hong，et al. A new large direct shear apparatus for field and laboratory test(II)：proof-testing[J]. Rock and Soil Mechanics，2006，27(2)：336–340.(in Chinese))
[16] BAHAADDINI M，HAGAN P，MITRA R，et al. Scale effect on the shear behaviour of rock joints based on a numerical study[J]. Engineering Geology，2014，181：212–223.
[17] 徐 磊，任青文. 分形节理抗剪强度尺寸效应的数值试验[J]. 采矿与安全工程学报，2007，24(4)：405–408.(XU Lei，REN Qingwen. Numerical test for size effect of shear strength of fractal joints[J] Journal of Mining and Safety Engineering，2007，24(4)：405–408.(in Chinese))
[18] J MURALHA，G GRASSELLI，B TATONE，et al. ISRM suggested method for laboratory determination of the shear strength of rock joints：Revised version[J]. Rock Mechanics and Rock Engineering，2014，47：291–302.
[19] 陈 琼，杜时贵，罗战友. 抗剪强度直剪仪的机制分析和测控系统开发[J]. 机床与液压，2017，45(13)：105–109.(CHEN Qiong，DU Shigui，LUO Zhanyou. Principle analysis and development of measurement and control system with direct shear apparatus for testing shear strength[J]. Machine Tool and Hydraulics，2017，45(13)：105–109.(in Chinese))
[20] LV Y J，DU S G，LUO Z Y，et al. Development and application of an integrative direct shear apparatus for multi-scale rock mass discontinuity[J]. Journal of Applied Sciences，2013，13(9)：1 558–1 563.
[21] 吕原君，杜时贵，罗战友，等. 多尺度岩体结构面抗剪强度直剪试验一体机的分级和验证[J]. 工程设计学报，2014，21(5)：481–486. (LV Yuanjun，DU Shigui，LUO Zhanyou，et al. Classification and Verification of an integrative direct shear apparatus for multi-scale rock mass discontinuity[J]. Chinese Journal of Engineer Design，2014，21(5)：481–486.(in Chinese))
[22] MORAD D，SAGY A，YH HATZOR. The significance of displacement control mode in direct shear tests of rock joints[J]. International Journal of Rock Mechanics and Mining Sciences，2020，134：1–8. |
|
|
|
2021, Vol. 40 
