Mechanical response characteristics and damage evolution mechanisms of deep rock masses under coupled loading–unloading-support-disturbance effects

Abstract

To reveal the mechanical response characteristics of deep rock masses under the complete engineering disturbance chain of "stress loading, excavation unloading, support reinforcement, and cyclic disturbance,” this study employed a true triaxial testing system combined with acoustic emission monitoring to conduct rock mass failure tests under coupled loading–unloading-support-disturbance actions. Results indicate that unloading is the dominant factor inducing rock mass damage and degradation, reducing strength by 31.57% compared to static loading. The superimposed disturbance effect further decreases the strength by 17.40%. Support partially restored rock strength and stiffness, increasing them by 7.29% and 10.37%, respectively, compared with pure unloading. Unloading increased dissipated energy per stress increment, and support achieved a dual effect of "energy dissipation and damage suppression” by inhibiting repeated crack reopening. Along the undisturbed path, damage accumulated slowly early and then exhibits a concentrated late-stage jump. Under disturbance, damage followed an "increase during loading, gradual change during unloading, and sharp surge at failure” pattern, with a markedly smaller rise in the damage variable at final instability than under the undisturbed path. Under disturbed conditions, intact rock showed the Kaiser effect, whereas unloaded rock subsequently exhibited the Felicity effect, supporting delayed Felicity onset, enhancing stress memory and disturbance resistance.

Keywords

True triaxial / Single side unloading / Cyclic disturbance / Acoustic emission / Mechanical response

References

[1] Cui QZ, Hou RB, Li ZH, Du F, Chen X, Zhang BY, et al. Time—dependent behavior of deep roadway surrounding rock considering damage induced by excavation and mining disturbances: Experiments, modeling, and simulation. Int J Min Sci Technol 2026; 36(2): 439-56.

[2] Wang B, He BG, Feng XT, Li HP. Fracturing mechanism of pre—damaged granite induced by multi—source dynamic disturbances in tunnels. Int J Min Sci Technol 2025; 33(9): 1439-59.

[3] He MC, Ren FQ, Liu DQ, Zhang SD. Experimental study on strain burst characteristics of sandstone under true triaxial loading and double faces unloading in one direction. Rock Mech Rock Eng 2021; 54(1): 149-71.

[4] Li KH, Du GZ, Han DY, Yin ZY, Li JT, Lin H. Mechanical and acoustic emission characteristics of anisotropic rock subjected to tiered cyclic intermediate principal stress. Eng Geol 2021. 358 108403—108403.

[5] Sun FY, Guo JQ, Liu XL, Zhang HY. Strain rockburst evolution process under true triaxial condition with single face unloading due to tunnel excavation. Comput Geotech 2023; 159: 105465.

[6] Gong HL, Luo Y, Xu K, Wang XY, Tao YH, Li XP. Mechanical characteristics of failure and rockburst proneness of fractured granite from Shuangjiangkou hydropower station under triaxial loading and unloading. Bull Eng Geol Environ 2023; 82(7): 256.

[7] Xiang TB, Feng XT, Chen BR, Jiang Q. True triaxial and acoustic emission experimental study of failure process of hard rock under excavating and supporting stress paths. Rock Soil Mech 2008; 29(S1): 500-6.in Chinese.

[8] Wang WJ, Han S, Dong EY, Peng G. Simulation on anchorage mechanism of rock mass. J China Coal Soc 2023; 48(1): 177-84.in Chinese.

[9] Han S, Wang WJ, Dong EY, Peng G. Control method of butterfly plastic zone of roadway surrounding rock based on support interference. J Min Saf Eng 2023; 40(4): 743—53.in Chinese.

[10] Duan MK, Jiang CB, Yin WM, Yang K, Li JZ, Liu QJ. Experimental study on mechanical and damage characteristics of coal under true triaxial cyclic disturbance. Eng Geol 2021; 295.

[11] Wang RH, Wei C, Liu J, Li Z, Tan YH. Macro and micro characteristics of jointed sandstone under cyclic loading and unloading. Chin J Rock Mech Eng 2023; 42(4): 810—20.in Chinese.

[12] Zheng Z, Li RH, Pan PZ, Qi JH, Su GS, Zheng H. Shear failure behaviors and degradation mechanical model of rockmass under true triaxial multi—level loading and unloading shear tests. Int J Min Sci Technol 2024; 34(10): 1385—408.

[13] Peng RD, Ju Y, Wang JG, Xie HP, Gao F, Mao LT. Energy dissipation and release during coal failure under conventional triaxial compression. Rock Mech Rock Eng 2015; 48(2): 509—26.

[14] Ma CD, Tan GS, Yang WY, Kang ZH, Zhang GY. Energy dissipation characteristics of sandstone under triaxial extension with different confining pressures. J Cent South Univ 2025; 32(6): 2195-207.

[15] Zhou X, Liu XF, Wang XR, Liu YB, Xie H, Du PF. Acoustic emission characteristics of coal failure under triaxial loading and unloading disturbance. Rock Mech Rock Eng 2022; 56(2): 1043-61.

[16] Feng XT, Gao YH, Zhang XW, Wang ZF, Zhang Y, Han Q. Evolution of the mechanical and strength parameters of hard rocks in the true triaxial cyclic loading and unloading tests. Int J Rock Mech Min Sci 2020; 131: 104349.

[17] Meng B, Jing HW, Yang XX, Chen KF, Yang SQ. Exprimental study of deformation and failure characteristics of anchorage unit in fractured surrounding rocks. Chin J Rock Mech Eng 2013; 32(12): 2497-505.in Chinese.

[18] Zhao GM, Xu WS, Meng XR, Liu CY. Instability mechanism of high stress rock mass under excavation and unloading induced by disturbance. J China Coal Soc 2020; 45(3): 936—48.in Chinese.

[19] He MC, Wang Q. Excavation compensation method and key technology for surrounding rock control. Eng Geol 2022; 307: 106784.

[20] Qi MJ, Zhao GM, Meng XR, Liu CY, Xu WS, Xu X, et al. Characterization of rock damage evolution and support timing under true triaxial unloading paths. J Cent South Univ 2026; 33(1): 442-65.

[21] Kang HP, Yi BD, Gao FQ, Lyu HW. Database and characteristics of underground in—situ stress distribution in Chinese coal mines. J China Coal Soc 2019; 44(1): 23-33.in Chinese.

[22] Chen J, Jiang Q, Feng XT, Hu YR. Experiment study of time—dependent deformation and failure of original damage marble. Adv Eng Sci 2018; 50(5): 27-37.in Chinese.

[23] Hu MT, Xu WY, Wang HL, Ning Y, Wang RB, Lyu CH, et al. Deformation characteristics of muddy sandstones during cyclic loading and unloading with different stress lower limits under pore pressure. Int J Fatigue 2023; 172.

[24] Liu HY, He BG, Guan JH, Fu HY. Experimental study on rock damage and failure induced by multi—source dynamic disturbances. Undergr Space 2026; 26(1): 364-86.

[25] Meng QB, Wang CK, Huang BX, Pu H, Zhang ZZ, Sun W, Wang J. Rock energy evolution and distribution law under triaxial cyclic loading and unloading conditions. Chin J Rock Mech Eng 2020; 39(10): 2047—59.in Chinese.

[26] Song ZY, Frühwirt T, Konietzky H. Characteristics of dissipated energy of concrete subjected to cyclic loading. Constr Build Mater 2018; 168: 47-60.

[27] Yong T, Hong TS, Yao HW, Lu YY. Mechanisms of stress memory formation and decay in granite via multi—parameter acoustic emission. Meas 2026. 279 121841—121841.

[28] Sun H, Liu XL, Zhu JB. Correlational fractal characterisation of stress and acoustic emission during coal and rock failure under multilevel dynamic loading. Int J Rock Mech Min Sci 2019. 1171-10.

[29] Ju SY, Li DS, Jia JQ. Machine—learning—based methods for crack classification using acoustic emission technique. Mech Syst Sig Process 2022; 178.

[30] Du K, Li XF, Tao M, Wang SF. Experimental study on acoustic emission (AE) characteristics and crack classification during rock fracture in several basic lab tests. Int J Rock Mech Min Sci 2020; 133: 104411.

[31] Liang XQ, Zhao YF, Cai FJ, Xiao TL, Jiang X. Effect of calcined coal gangue powder on the properties of basalt fiber—reinforced concrete. Constr Build Mater 2026. 516 145662—145662.