Excess energy characteristics of true triaxial multi-faceted rapid unloading rockburst

Abstract

Delayed rockburst experiments with different numbers of unloading surfaces (DNUS) were performed using an independently developed true triaxial multisurface unloading rockburst experimental system. Based on the rockburst excess energy theory, the energy storage characteristics, excess energy, excess energy release rate (EERR), and crack evolution characteristics of rockbursts with DNUS were studied, and the following main conclusions were obtained. The occurrence of rockbursts is mainly due to the generation of an excess energy ΔE. ΔE depends on the elastic strain energy stored in the rock before the rockburst, the energy input by the equipment after the peak, and the residual elastic strain energy. As the DNUS increases, ΔE gradually decreases, but the EERR value increases, and the rockburst becomes increasingly severe; Rapid unloading of the specimen under true triaxial high-pressure loading will produce an unloading platform in the stress–strain curve, causing unloading damage. The damage is mainly concentrated near the free surface in the form of tension failure, and the unloading damage gradually increases with increasing DNUS; Tensile cracks play a dominant role in the damage and destruction of sandstone. In the final rockburst stage, the slope of the shear crack curve was greater than that of the tensile cracks, indicating that shear cracks were a critical factor affecting the instability and failure of the specimen.

Keywords

True triaxial rockburst experiment / excess energy / excess energy release rate / rapid unloading / crack evolution

References

[1] HeM-c, RenF-q, LiuD-qiao. Rockburst mechanism research and its control. International Journal of Mining Science and Technology, 2018, 28(5): 829-837 J]

[2] LiX-b, GongF-q, TaoM, et al. . Failure mechanism and coupled static-dynamic loading theory in deep hard rock mining: A review. Journal of Rock Mechanics and Geotechnical Engineering, 2017, 9: 767-782 J]

[3] OrtleppW D, StaceyT R. Rockburst mechanisms in tunnels and shafts. Tunnelling and Underground Space Technology, 1994, 9(1): 59-65 J]

[4] HeM-c, XieH-p, PengS-p, et al. . Study on rock mechanics in deep mining engineering. Chinese Journal of Rock Mechanics and Engineering, 2005, 24(16): 2803-2813[J]

[5] WangC-l, HeB-b, HouX-l, et al. . Stress-energy mechanism for rock failure evolution based on damage mechanics in hard rock. Rock Mechanics and Rock Engineering, 2020, 53(3): 1021-1037 J]

[6] HeM C, MiaoJ L, FengJ L. Rock burst process of limestone and its acoustic emission characteristics under true-triaxial unloading conditions. International Journal of Rock Mechanics and Mining Sciences, 2010, 47(2): 286-298 J]

[7] HeM C, NieW, ZhaoZ Y, et al. . Experimental investigation of bedding plane orientation on the rockburst behavior of sandstone. Rock Mechanics and Rock Engineering, 2012, 45(3): 311-326 J]

[8] LiX-b, GongF-q, WangS-f, et al. . Coupled static-dynamic loading mechanical mechanism and dynamic criterion of rockburst in deep hard rock mines. Chinese Journal of Rock Mechanics and Engineering, 2019, 38(4): 708-723[J]

[9] LiX-b, DuK, LiD-yuan. True triaxial strength and failure modes of cubic rock specimens with unloading the minor principal stress. Rock Mechanics and Rock Engineering, 2015, 48(6): 2185-2196 J]

[10] HeM-c, LiuD-q, GongW-l, et al. . Development of a testing system for impact rockbursts. Chinese Journal of Rock Mechanics and Engineering, 2014, 33(9): 1729-1739[J]

[11] FengG-l, ChenB-r, JiangQ, et al. . Excavation-induced microseismicity and rockburst occurrence: Similarities and differences between deep parallel tunnels with alternating soft-hard strata. Journal of Central South University, 2021, 28(2): 582-594 J]

[12] WangC-l, CaoC, LiC-f, et al. . Experimental investigation on synergetic prediction of granite rockburst using rock failure time and acoustic emission energy. Journal of Central South University, 2022, 29(4): 1262-1273 J]

[13] XuW-s, ZhaoG-m, MengX-r, et al. . Test study on true-triaxial loading and unloading for marble with unloaded single face. Journal of Southwest Jiaotong University, 2019, 54(3): 526-534[J]

[14] LiuD-q, LingK, LiD, et al. . Evolution of anisotropy during sandstone rockburst process under double-faces unloading. Journal of Central South University, 2021, 28(8): 2472-2484 J]

[15] WuW-x, GongF-q, ZhangZ-xian. Sidewall rockburst of highly stressed D-shape hole tunnel triggered by impact load: An experimental investigation. Rock Mechanics Bulletin, 2024, 3(1): 100094 J]

[16] CookN. The basic mechanics of rockbursts. Journal of the Southern African Institute of Mining and Metallurgy, 1963, 64371-81[J]

[17] CookN. A note on rockbursts considered as a problem of stability. Journal of the Southern African Institute of Mining and Metallurgy, 1965, 65(8): 437-446[J]

[18] WalshJ B. Energy changes due to mining. International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, 1977, 14(1): 25-33 J]

[19] WangJ A, ParkH D. Comprehensive prediction of rockburst based on analysis of strain energy in rocks. Tunnelling and Underground Space Technology, 2001, 16(1): 49-57 J]

[20] GongF-q, YanJ-y, LiX. A new criterion of rock burst proneness based on the linear energy storage law and the residual elastic energy index. Chinese Journal of Rock Mechanics and Engineering, 2018, 37(9): 1993-2014[J]

[21] HeM-c, XiaH-m, JiaX-n, et al. . Studies on classification, criteria and control of rockbursts. Journal of Rock Mechanics and Geotechnical Engineering, 2012, 4(2): 97-114 J]

[22] HeM-c, LiJ-y, LiuD-q, et al. . A novel true triaxial apparatus for simulating strain bursts under high stress. Rock Mechanics and Rock Engineering, 2021, 54(2): 759-775 J]

[23] LiuX-x, LiangZ-z, ZhangY-b, et al. . Experimental study on the monitoring of rockburst in tunnels under dry and saturated conditions using AE and infrared monitoring. Tunnelling and Underground Space Technology, 2018, 82: 517-528 J]

[24] CaiM, KaiserPK. Rockburst support reference book—Volume I: Rockburst phenomenon and support characteristics. Laurentian University, 2018, 284: 697-699[J]

[25] EsterhuizenG S, DolinarD R, EllenbergerJ L. Pillar strength in underground stone mines in the United States. International Journal of Rock Mechanics and Mining Sciences, 2011, 48(1): 42-50 J]

[26] SIMON R, AUBERTIN M, DENG D. Estimation of post-peak behaviour of brittle rocks using a constitutive model for rock joints [C]// 56th Canadian Geotechnical Conference. 2003.

[27] KhosraviA, SimonR. Verification of the Csds model in estimating the postpeak behavior of hard rocks. International Journal of Geomechanics, 2018, 18(3): 04017166 J]

[28] HeM-c, RenF-q, LiuD-q, et al. . Experimental study on strain burst characteristics of sandstone under true triaxial loading and double faces unloading in one direction. Rock Mechanics and Rock Engineering, 2021, 541149-171 J]

[29] CaiX, ChengC-q, ZhouZ-l, et al. . Rock mass watering for rock-burst prevention: Some thoughts on the mechanisms deduced from laboratory results. Bulletin of Engineering Geology and the Environment, 2021, 80(11): 8725-8743 J]

[30] LiJ-y, HeM-c, LiuD-q, et al. . Comparative experimental investigation on true triaxial double-sided fast unloading rockburst and biaxial compression under high stress. Canadian Geotechnical Journal, 2023, 60(8): 1202-1215 J]

[31] LiJ-y, LiuD-q, HeM-c, et al. . True triaxial experimental study on the variation characteristics of rockburst with the number of fast unloading surfaces. Rock Mechanics and Rock Engineering, 2023, 56(8): 5585-5606 J]

[32] ShahidanS, PulinR, Muhamad BunnoriN, et al. . Damage classification in reinforced concrete beam by acoustic emission signal analysis. Construction and Building Materials, 2013, 45: 78-86 J]

[33] LiuY-h, NieZ-p, LiuQ-huo. DIFFT: A fast and accurate algorithm for Fourier transform integrals of discontinuous functions. IEEE Microwave and Wireless Components Letters, 2008, 18(11): 716-718 J]

[34] AggelisD G, SouliotiD V, SapouridisN, et al. . Acoustic emission characterization of the fracture process in fibre reinforced concrete. Construction and Building Materials, 2011, 25(11): 4126-4131 J]

[35] OhnoK, OhtsuM. Crack classification in concrete based on acoustic emission. Construction and Building Materials, 2010, 24(12): 2339-2346 J]

[36] OhtsuM. Quantitative AE techniques standardized for concrete structures. Advanced Materials Research, 2006, 13–14: 183-192 J]

[37] ZhouX, LiuX-f, WangX-r, et al. . Acoustic emission characteristics of coal failure under triaxial loading and unloading disturbance. Rock Mechanics and Rock Engineering, 2023, 56(2): 1043-1061 J]