Study on mechanical properties and mesoscopic damage mechanism of composite jointed rock masses

Abstract

Joints are widely distributed structural defects in rock masses, and their geometric characteristics play a decisive role in the overall stability of rocks under complex stress conditions. To clarify the influence of joint geometry on the mechanical behavior of jointed rock under such conditions, this study investigated the mechanical properties and failure mechanisms of composite jointed rock specimens with varying joint roughness and joint dip angles. Three typical failure modes under triaxial loading were identified, and a mechanical analysis model incorporating joint roughness and dip angle was established. The failure mechanism was revealed, and a discrete element model was developed to analyze the micro-damage evolution process of the specimens. The results show that the mechanical parameters of the specimens exhibit pronounced anisotropy. Both the elastic modulus and peak strength reach their minimum values at a joint dip angle of 60 °. Increasing joint roughness significantly reduces the degree of anisotropy and enhances the energy storage capacity of the specimens. A strong linear relationship is observed between the elastic strain energy and the peak deviatoric stress, confirming the applicability of the linear energy storage law in composite jointed rocks. Discrete element simulations revealed the evolution path and dominant types of microcracks between the joint and matrix. The joint dip angle governs the transition of dominant crack types from tensile to shear and then back to tensile. Increased joint roughness significantly suppresses damage localization along the joint and results in an approximately 20% increase in the proportion of shear microcracks within the matrix. These findings clarify the regulatory role of joint geometrical parameters in the damage evolution process.

Keywords

Composite jointed rock mass / Joint roughness coefficient (JRC) / Failure mode / Energy evolution / Damage parameter

Acknowledgements

This research was supported by the National Natural Science Foundation of China (Nos. 52304108, 52274148), and China University of Mining and Technology-Beijing Undergraduate Inno-vation Training Program (No. 202515011).

References

[1] Deng HW, Liu CJ, Ke B, Wang Y, Zhang YN. Experimental study on microscopic damage characteristics of granite under cyclic dynamic disturbances. Chin J Eng 2017; 39(11):1634-9. In Chinese.

[2] Qian QH. Challenges faced by underground projects construction safety and countermeasures. Chin J Rock Mech Eng 2012; 31(10):1945-56. In Chinese.

[3] Liu XR, Kou MM, Lu YM, Liu YQ. An experimental investigation on the shear mechanism of fatigue damage in rock joints under pre-peak cyclic loading condition. Int J Fatigue 2018; 106:175-84.

[4] Brace WF, Kohlstedt DL. Limits on lithospheric stress imposed by laboratory experiments. J Geophys Res Solid Earth 1980; 85(B11):6248-52.

[5] Zheng Z, Deng B, Liu H, Wang W, Huang S, Li S. Microdynamic mechanical properties and fracture evolution mechanism of monzogabbro with a true triaxial multilevel disturbance method. Int J Min Sci Technol 2024; 34 (3):385-411.

[6] Wang ZC, Shi WC, Kong R, Guo JF. Mechanical properties of deep sandstone under true triaxial stress. J Northeast Univ Nat Sci 2023; 44(5):689-96. In Chinese.

[7] Shan RL, Liu NZ, Sun P, Zhao ZY, Dong RY, Dou HY, Bai Y. Experimental and numerical simulation study of rough jointed rock samples under triaxial compression conditions. Eng Fract Mech 2025; 314:110707.

[8] He M, Peng Y, Zhao S, Shi H, Wang N, Gong W. Fracture mechanism of inversed trapezoidal shaped tunnel excavated in 45 inclined rock strata. Int J Min Sci Technol 2015; 25(4):531-5.

[9] Abbas N, Li KG, Fissha Y, Khatti J, Geberegergis MB, Cheepu rupalli NR, Chandrahas NS. Reliability analysis of support strategies in tunnel construction: Insights from geomechanical analysis of jointed rock masses. Results Earth Sci 2024; 2:100044.

[10] Zhang H, Lu CP, Liu B, Liu Y, Zhang N, Wang HY. Numerical investigation on crack development and energy evolution of stressed coal-rock combination. Int J Rock Mech Min Sci 2020; 133:104417.

[11] Liu XG, Zhu WC, Zhang PH, Li LK. Failure in rock with intersecting rough joints under uniaxial compression. Int J Rock Mech Min Sci 2021; 146:104832.

[12] Asadizadeh M, Hossaini MF, Moosavi M, Masoumi H, Ranjith PG. Mechanical characterisation of jointed rock-like material with non-persistent rough joints subjected to uniaxial compression. Eng Geol 2019; 260:105224.

[13] Huang SB, Liu QS, Liu YZ, Kang YS, Cheng AP, Ye ZY. Frost heaving and frost cracking of elliptical cavities (fractures) in low-permeability rock. Eng Geol 2018; 234:1-10.

[14] Yan YT, Wang SW. Simulation investigation of mechanical and failure characteristics of jointed rock with different shapes of joint asperities under compression loading. Computational Particle Mechanics 2023; 10(1):45-59.

[15] Yuan P, Li AB, Chen CN, Lu XF.Experimental study of uniaxial compressive mechanical properties of rough jointed rock masses based on 3D printing. Appl Rheol 2023; 33:20230114.

[16] Peellage WH, Fatahi B, Rasekh H. Experimental investigation for vibration characteristics of jointed rocks using cyclic triaxial tests. Soil Dyn Earthq Eng 2022; 160:107377.

[17] Chen QZ, Liu YM, Pu SY. Strength characteristics of nonpenetrating joint rock mass under different shear conditions. Adv Civ Eng 2020; 2020(1):3579725.

[18] Yin DW, Chen SJ, Ge Y, Liu R. Mechanical properties of rock-coal bi-material samples with different lithologies under uniaxial loading. J Mater Res Technol 2021; 10:322-38.

[19] Liu XB, He SH, Wang DH. Numerical analysis of the anisotropy and scale effects on the strength characteristics of defected rockmass. Adv Civ Eng 2020; 2020 (1):5892924.

[20] Ma Q, Tan YL, Liu XS, Zhao ZH, Fan DY. Mechanical and energy characteristics of coal-rock composite sample with different height ratios: a numerical study based on particle flow code. Environ Earth Sci 2021; 80(8):309.

[21] He YC, Zhao PX, Li SG, Ho CH, Zhu ST, Kong XG, Barbieri DM. Mechanical properties and energy dissipation characteristics of coal-rock-like composite materials subjected to different rock-coal strength ratios. Nat Resour Res 2021; 30(3):2179-93.

[22] Liu XW, Liu QS, Kang YS, Pan YC. Improved nonlinear strength criterion for jointed rock masses subject to complex stress states. Int J Geomech 2018; 18 (3):04017164.

[23] Han Y, Zhao YM, Li JL. Experimental and numerical study of strength and failure behavior of precracked marble under true triaxial compression. Shock Vib 2021; 2021(1):3869045.

[24] Chi XL, Yang K, Wei Z. Investigation of energy and damage evolutions in rock specimens with large-scale inclined prefabricated cracks by uniaxial compression test and AE monitoring. Adv Civ Eng 2020; 2020(1):8887543.

[25] Wang YY, Yang HQ, Song KL, Chen CW, Li H, Li XY. The influence of joint distribution characteristics on the mechanical properties, fracture mechanisms, and energy characteristics of rock masses under stress conditions. Comput Geotech 2025; 178:106933.

[26] Zhang HQ, Shi H, Zhao HY, Song L. Characterization of transverse vibration response of resin-anchored bolt under axial tension and life cycle health assessment of anchorage debonding. Measurement 2025; 256:118273.

[27] Yin PF, Yang SQ. Experimental study on strength and failure behavior of transversely isotropic rock-like material under uniaxial compression. Geomech Geophys Geo Energy Geo Resour 2020; 6(3):44.

[28] Meng YY, Jing HW, Zhou ZF, Zhang L, Sun SH. Experimental investigation on the mixed-mode fracture behavior of rock-like material with bedding plane. Theor Appl Fract Mech 2022; 117:103159.

[29] Liu HB, Cui S, Meng YF, Sun HR, Wang S, Du S. Study on the mechanical properties and failure law of rocks with interbedded sand and mud. ACS Omega 2022; 7(49):44804-16.

[30] Dou HY, Shan RL, Li GZ, Sun P, Bai Y, Qiu SH. Research on the Brazilian splitting characteristics and failure mechanism of jointed composite disks. mech Adv. Mater Struct 2025; 32(12):2762-77.

[31] Xie HP. Fractal description of rock joints. Chin J Geotech Eng 1995; 17(1):18-23. In Chinese.

[32] Kong LY, Ishutov S, Hasiuk F, Xu CC. 3D printing for experiments in petrophysics, rock physics, and rock mechanics: a review. SPE Reserv Eval Eng 2021; 24(4):721-32.

[33] Gell EM, Walley SM, Braithwaite CH. Review of the validity of the use of artificial specimens for characterizing the mechanical properties of rocks. Rock Mech Rock Eng 2019; 52(9):2949-61.

[34] Bai Y, Shan RL, Wu YX, Sun PF. Development and application of a new triaxial testing system for subzero rocks. Geotech Test J 2021; 44(5):1327-49.

[35] Shi XD, Feng GR, Bai JW, Zhu C, Wang SY, Wang K, Song C. Brazil splitting characteristics of coal-backfilling composite structure with different interface angles: Insights from laboratory experiment and numerical simulation. J Cent South Univ 2023; 30(1):189-201.

[36] Meng YY, Jing HW, Sun SH, Chen M, Huang K. Experimental and numerical studies on the anisotropic mechanical characteristics of rock-like material with bedding planes and voids. Rock Mech Rock Eng 2022; 55(11):7171-89.

[37] Zhang ZH, Liang ZZ, Tang CA, Kishida K. A comparative study of current methods for determining stress thresholds of rock subjected to compression. Rock Mech Rock Eng 2023; 56(11):7795-818.

[38] Gao L, Gao F, Zhang ZZ, Xing Y. Research on the energy evolution characteristics and the failure intensity of rocks. Int J Min Sci Technol 2020; 30(5):705-13.

[39] Zhang JW, Song ZX, Wang SY. Experimental investigation on permeability and energy evolution characteristics of deep sandstone along a three-stage loading path. Bull Eng Geol Environ 2021; 80(2):1571-84.

[40] Hou ZK, Gutierrez M, Ma SQ, Almrabat A, Yang CH. Mechanical behavior of shale at different strain rates. Rock Mech Rock Eng 2019; 52(10):3531-44.

[41] Gong FQ, Zhang PL, Luo S, Li JC, Huang D.Theoretical damage characterisation and damage evolution process of intact rocks based on linear energy dissipation law under uniaxial compression. Int J Rock Mech Min Sci 2021; 146:104858.

[42] Xu L, Gong FQ, Luo S. Effects of pre-existing single crack angle o n mechanical behaviors and energy storage characteristics of red sandstone under uniaxial compression. Theor Appl Fract Mech 2021; 113:102933.