Experimental insights into anchorage performance of en-echelon joints under cyclic shear loading

Abstract

Understanding the anchorage performance of en-echelon joints under cyclic shear loading is crucial for optimizing support strategies in jointed rock masses. This study examines the anchorage effects on en-echelon joints with various orientations using laboratory cyclic shear tests. By comparing unbolted and bolted en-echelon joints, we analyze shear zone damage, shear properties, dilatancy, energy absorption, and acoustic emission characteristics to evaluate anchoring effects across shear cycles and joint orientations. Results reveal that bolted en-echelon joints experience more severe shear zone damage after cycles, with bolt deformation correlating to shear zone width. Bolted en-echelon joints exhibit faster shear strength deterioration and higher cumulative strength loss compared to unbolted ones, with losses ranging from 20.04% to 72.76%. The compressibility of en-echelon joints reduces the anchoring effect during shear cycles, leading to lower shear strength of bolted en-echelon joints in later stages of shear cycles compared to unbolted ones. Bolts reinforce en-echelon joints more effectively at non-positive angles, with the best performance observed at 0° and -60°. Anchorage accelerates the transition from rolling friction to sliding friction in the shear zone, enhancing energy absorption, which is crucial for rock projects under dynamic shear loading. Additionally, rock bolts expedite the transition of the cumulative AE hits and cumulative AE energy curves from rapid to steady growth, indicating that strong bolt-rock interactions accelerate crack initiation, propagation, and energy release.

Keywords

En-echelon joints / Shear strength deterioration / Cyclic shear test / Anchorage performance / Energy absorption characteristics / Acoustic emission

Acknowledgments

This work was financially supported by the National Natural Science Foundation of China (No. 42172292), Taishan Scholars Project Special Funding, and Shandong Energy Group (No. SNKJ2022A01-R26). The first author is funded by the China Scholarship Council (CSC No. 202006220274).

References

[1] Kim YS, Peacock DCP, Sanderson DJ. Mesoscale strike-slip faults and damage zones at Marsalforn, Gozo Island. Malta J Struct Geol 2003; 25(5):793-812.

[2] Gehle C, Kutter HK. Breakage and shear behaviour of intermittent rock joints. Int J Rock Mech Min Sci 2003; 40(5):687-700.

[3] Dang WG, Konietzky H, Frühwirt T, Herbst M. Cyclic frictional responses of planar joints under cyclic normal load conditions: Laboratory tests and numerical simulations. Rock Mech Rock Eng 2020; 53(1):337-64.

[4] Li YK, Zhao TB, Li YF, Chen Y. A five-parameter constitutive model for hysteresis shearing and energy dissipation of rock joints. Int J Min Sci Technol 2022; 32(4):737-46.

[5] Jiang Q, Liu XP, Li SJ, Liu J, Liu Q, Sun WL. Coupling deterioration model of mechanical parameters for the Jinping marble under progressive damage conditions. Rock Mech Rock Eng 2023; 56(6):3993-4018.

[6] Fan DY, Liu XS, Tan YL, Li XB, Yang SL. Energy mechanism of bolt supporting effect to fissured rock under static and dynamic loads in deep coal mines. Int J Min Sci Technol 2024; 34(3):371-84.

[7] Lee HS, Park YJ, Cho TF, You KH. Influence of asperity degradation on the mechanical behavior of rough rock joints under cyclic shear loading. Int J Rock Mech Min Sci 2001; 38(7):967-80.

[8] Plesha ME. Constitutive models for rock discontinuities with dilatancy and surface degradation. Int J Numer Anal Meth Geomech 1987; 11(4):345-62.

[9] Jafari MK, Amini Hosseini K, Pellet F, Boulon M, Buzzi O. Evaluation of shear strength of rock joints subjected to cyclic loading. Soil Dyn Earthq Eng 2003; 23 (7):619-30.

[10] Belem T, Souley M, Homand F. Modeling surface roughness degradation of rock jointwallduringmonotonicandcyclicshearing.ActaGeotech 2007; 2(4):227-48.

[11] Mirzaghorbanali A, Nemcik J, Aziz N. Effects of shear rate on cyclic loading shear behaviour of rock joints under constant normal stiffness conditions. Rock Mech Rock Eng 2014; 47(5):1931-8.

[12] Zhang YC, Huang M, Jiang YJ, Wang Z. Mechanics, damage and energy degradation of rock-concrete interfaces exposed to high temperature during cyclic shear. Constr Build Mater 2023;405:133229.

[13] Wang B, Jiang YJ, Zhang QY, Zhang YC. Cyclic shear behavior of en-echelon joints under constant normal load. Eng Geol 2023;325:107308.

[14] Wang B, Jiang YJ, Zhang QY, Chen HB, Liu RC, Zhang YC. Cyclic shear behavior of en-echelon joints under constant normal stiffness conditions. J Rock Mech Geotech Eng 2024; 16(9):3419-36.

[15] Wang B, Jiang YJ, Zhang QY, Chen HB. Effects of joint persistence and testing conditions on cyclic shear behavior of en-echelon joints under CNS conditions. Rock Mech Bull 2024; 3(4):100147.

[16] Wang B, Jiang YJ, Zhang QY, Chen HB. Mechanical behavior of en-echelon joints under cyclic shear loading conditions: Roles of joint persistence and loading conditions. Theor Appl Fract Mech 2024;134:104746.

[17] Wang B, Jiang YJ, Zhang QY, Chen HB, Liu RC. Experimental investigation on the cyclic shear behavior of intermittent joints. Int J Rock Mech Min Sci 2024;181:105854.

[18] Wang B, Jiang YJ, Zhang QY, Chen HB. Shear behaviors of intermittent joints subjected to shearing cycles under constant normal stiffness conditions: Effects of loading parameters. J Rock Mech Geotech Eng 2024.

[19] Wu XZ, Jiang YJ, Gong B, Deng T, Guan ZC. Behaviour of rock joint reinforced by energy-absorbing rock bolt under cyclic shear loading condition. Int J Rock Mech Min Sci 2018;110:88-96.

[20] Wu XZ, Zheng HF, Jiang YJ, Deng T, Xiao GS, Wang Y. Effect of cyclic shear loading on shear performance of rock bolt under different joint roughness. Rock Mech Rock Eng 2023; 56(3):1969-80.

[21] Jiang Y, Xiao J, Tanabashi Y, Mizokami T. Development of an automated servocontrolled direct shear apparatus applying a constant normal stiffness condition. Int J Rock Mech Min Sci 2004; 41(2):275-86.

[22] Zhang YC, Jiang YJ, Wang Z, Yin Q, Chen M. Anchorage effect of bolt on enechelon fractures: A comparison between energy-absorbing bolt and conventional rigid bolt. Eng Fail Anal 2022;137:106256.

[23] Bowden FP, Tabor D. The area of contact between stationary and moving surfaces. Proc R Soc Lond A 1939; 169(938):391-413.

[24] Bowden FP, Tabor D. Mechanism of metallic friction. Nature 1942; 150 (3798):197-9.

[25] Ikari MJ, Carpenter BM, Marone C. A microphysical interpretation of rate- and state-dependent friction for fault gouge. Geochem Geophys Geosyst 2016; 17 (5):1660-77.

[26] Anthony JL, Marone C. Influence of particle characteristics on granular friction. J Geophys Res Solid Earth 2005;110:B08409.

[27] Abe S, Mair K. Effects of gouge fragment shape on fault friction: New 3D modelling results. Geophys Res Lett 2009; 36(23):2009GL040684.

[28] Zhang YC, Jiang YJ, Asahina D, Wang Z. Shear behavior and acoustic emission characteristics of en-echelon joints under constant normal stiffness conditions. Theor Appl Fract Mech 2020;109:102772.

[29] Huang Z, Gu QX, Wu YF, Wu Y, Li SJ, Zhao K, Zhang R. Effects of confining pressure on acoustic emission and failure characteristics of sandstone. Int J Min Sci Technol 2021; 31(5):963-74.

[30] Xing YK, Huang BX, Zhang GQ, Li BH, Xu H, Jiao XJ, Yu Y, Han T, Chen J. Identifying the real fracture hidden in rock microcrack zone by acoustic emission energy. Int J Min Sci Technol 2024; 34(6):731-46.

[31] Jiang Q, Xin J, Xu DP, Liu Q. Shear failure process of rectangular tunnel: Physical experimental test and numerical back-analysis. Theor Appl Fract Mech 2022;120:103384.

[32] He MC, Ren SL, Guo LJ, Lin WJ, Zhang TW, Tao ZG. Experimental study on influence of host rock strength on shear performance of Micro-NPR steel bolted rock joints. Int J Rock Mech Min Sci 2022;159:105236.

[33] Dight PM. Improvements to the stability of rock walls in open pit mines. Master’s dissertation. Melbourne: Monash University; 1982.

[34] Pinazzi PC, Spearing AJS, Jessu KV, Singh P, Hawker R. Mechanical performance of rock bolts under combined load conditions. Int J Min Sci Technol 2020; 30 (2):167-77.

[35] Tadolini SC, Derycke S, Bhagwat A. Characterization of tensile and shear loading on indented PC-strand cable bolts. Int J Min Sci Technol 2016; 26 (1):89-95.

[36] Jiang Q, Feng XT, Cui J, Li SJ. Failure mechanism of unbonded prestressed thruanchor cables: In situ investigation in large underground Caverns. Rock Mech Rock Eng 2015; 48(2):873-8.