Compressive-shear damage and acoustic emission response of grouted concrete in fault zones: Coupling effects of aggregate content and particle size

Abstract

Understanding aggregate effects within fault fracture zones is crucial for assessing fault reactivation risks in grouted deep coal mines. This study investigates the compressive-shear damage mechanisms of grouted concrete specimens with varying aggregate contents (20%, 40%, 60%) and particle sizes (1–5 mm, 6–10 mm). Uniaxial compressive-shear tests were monitored synchronously using digital image correlation (DIC) and acoustic emission (AE). Additionally, a calibrated PFC2D discrete element model, incorporating matrix, aggregate, and interfacial transition zones, elucidated the mesoscale mechanisms. Results indicate: (1) peak shear load decreases linearly (R² >0.86) with increasing aggregate content, dropping 64.3% from 20% to 60%, driving a transition from brittle to plastic failure; (2) AE b-value evolution tracks progressive damage, while damage rate k exhibits contrasting size-dependent trends; (3) macroscopic failure modes are synergistically controlled by aggregate size and content; and (4) numerical simulations validate the mesoscale mechanical origins of this brittle-to-plastic transition. These findings reveal the micro-mechanical mechanisms of anisotropic failure and re-strengthening in grouted fault materials, offering vital geological insights into stress evolution and instability precursors during fault reactivation.

Keywords

Fault grouting reinforcement / Compressive-shear damage / Aggregate effects / Acoustic emission / Multi-scale simulation

References

[1] Ma D, Duan HY, Zhang JX. Solid grain migration on hydraulic properties of fault rocks in underground mining tunnel: Radial seepage experiments and verification of permeability prediction. Tunn Undergr Space Technol 2022; 126:104525.

[2] Wang L, Kwiatek G, Renard F, Guérin—Marthe S, Rybacki E, Bohnhoff M, et al. Fault roughness controls injection—induced seismicity. PNAS 2024; 121(3):e2310039121.

[3] Cao ZZ, Yang XQ, Li ZH, Du F. Evolution mechanism of water—conducting fractures in overburden under the influence of water—rich fault in underground coal mining. Sci Rep 2024; 14:5081.

[4] Lan TW, Sun JW, Batugin AS, Zhao WQ, Zhang MC, Jia WD, et al. Dynamic characteristics of fault structure and its controlling impact on rock burst in mines. Shock Vib 2021; 2021:7954876.

[5] Jiang LS, Wang P, Zheng PQ, Luan HJ, Zhang C. Influence of different advancing directions on mining effect caused by a fault. Adv Civ Eng 2019; 2019:7306850.

[6] Feng XJ, Yue WT, Zhao X, Wang DM, Liu QL, Ding Z. Evolution law and risk analysis of fault—slip burst in coal mine based on microseismic monitoring. Environ Earth Sci 2025; 84(2):59.

[7] Liu SQ, Cheng ZC, Wang HL, Bao JR. Experimental and numerical study on grouting reinforcement of a broken rock mass. Int J Geomech 2025; 25(2):04024357.

[8] Du XM, Li ZH, Fang HY, Li B, Zhao XH, Zhai KJ, et al. A state—of—the—art review on the study of the diffusion mechanism of fissure grouting. Appl Sci 2024; 14(6):2540.

[9] Pan WP, Li HB, Hua XZ, Liu B, Li C. Research on grouting reinforcement technology of fault crossing roadway in fully mechanized mining face with large dip angle. Bull Eng Geol Environ 2024; 83(6):216.

[10] Le HL, Sun SR, Wei JH. Influence of types of grouting materials on compressive strength and crack behavior of rocklike specimens with single grout—infilled flaw under axial loads. J Mater Civ Eng 2019; 31:06018022.

[11] Liu Y, Wu ZJ, Weng L, Wu LJ, Zhou Y, Liu QS. Grouting diffusion characteristics in rough sandstone fracture with flowing water: Insights from NMR experimental investigation. Tunn Undergr Space Technol 2025; 157:106372.

[12] Li J, Xuan DY, Xu JL, Dong ZB, Wang CC. Compaction response of mining—induced rock masses to longwall overburden isolated grouting. Minerals 2023; 13(5):633.

[13] Lu HF, Yi JL, Liu QS, Cao AD, Wei AC, Zhang K. A self—dissolved grouting reinforcement method for water—rich soft rock roadway. Bull Eng Geol Environ 2022; 81(7):256.

[14] Li C, Lu CJ, Xu JP, Zhang K, Liu SM, Zhao H. Diffusion mechanism of variable—rate grouting in water prevention and control of coal mine. Water 2024; 16(19):2814.

[15] Gao YJ, Yao BH, Zhang HT, Zhang BY, Song JH, Wang Q, et al. Study on the test of coal mass fracture grouting sealing with coal—based materials and its application. Front Earth Sci 2023; 10:1089248.

[16] Shen QJ, Jiang RS, Cong BR, Guo BL, Shang HF, Ji XG. Study on the effect of mineral admixtures on working and mechanical properties of the grouting material. Front Mater 2023; 10:1197997.

[17] He XF, Hong QH, Chen Z, Tang G, Huang W. Environmental resistance investigation for shield inert synchronous grouting material based on slag powder, fly ash and silica fume. Eur J Environ Civ Eng 2025; 29(6):1196-213.

[18] Li JF, Liu YT, Li SJ, Song Y. Experimental investigation of synchronous grouting material prepared with different mineral admixtures. Materials 2022; 15(3):1260.

[19] Li ZP, Li SC, Liu HJ, Zhang QS, Liu YN. Experimental study on the reinforcement mechanism of segmented split grouting in a soft filling medium. Processes 2018; 6(8):131.

[20] Shi HX, Liu JP, Sun YF, Wang XN, Li FT. Study on the temporal—spatial evolution characteristics of micro—cracks during fault slip based on acoustic emission monitoring. Rock Mech Rock Eng 2025; 58(3):3417-35.

[21] Li Z, Liu JC, Xu RC, Liu HX, Shi WH. Study of grouting effectiveness based on shear strength evaluation with experimental and numerical approaches. Acta Geotech 2021; 16(12):3991-4005.

[22] Feng XJ, Yue WT, Cao ZW, Zhou SS, Cao XQ, Wang EY. Multi—scale DEM simulation and experimental validation of water—saturated coal failure under variable—angle shear loading: Revealing hydrochemical coupling damage mechanisms. Measurement 2026; 260:119812.

[23] Zhang QC, Li ZH, Niu Y, Yin S, Gao FT, Zhang FQ, et al. The response of electrical potential in sandstone of different sizes under cyclic loading. Measurement 2025; 256:118196.

[24] Guo YD, Huang LQ, Li XB, Chen JZ, Sun JN. Experimental investigation on the effects of thermal treatment on the physical and mechanical properties of shale. J Nat Gas Sci Eng 2020; 82:103496.

[25] Liu CF, Wang EY, Li BL, Li ZH, Wang Y. A knowledge—augmented generative—recognition—warning framework for precursor risk identification of coal and gas outbursts. Adv Eng Inf 2026; 74:104617.

[26] Zhou XP, Zhang JZ, Qian QH, Niu Y. Experimental investigation of progressive cracking processes in granite under uniaxial loading using digital imaging and AE techniques. J Struct Geol 2019; 126:129-45.

[27] Yun HS, Moon SW, Seo YS. Effects of breccia and water contents on the mechanical properties of fault—core—zone materials. Sci Rep 2022; 12:7093.

[28] Zhang D, Zhu QC, Bai JB, Wang R, Zhang ZZ, Fu H, et al. Theory and simulation investigations on stability control of gob—side entry retaining with coal pillar—backfill body system. Int J Min Sci Technol 2025; 35:1399-417.

[29] Lu ZG, Ju WJ, Gao FQ, Yi K. Influence of loading rate on the failure characteristics of composite coal—rock specimens under quasi—static loading conditions. Rock Mech Rock Eng 2022; 55(2):909-21.

[30] Du K, Li XF, Wang SY, Tao M, Li G, Wang SF. Compression—shear failure properties and acoustic emission (AE) characteristics of rocks in variable angle shear and direct shear tests. Measurement 2021; 183:109814.

[31] Wang H, Fall M, Miao SJ. Characteristics of fracture changes and fatigue failure signals for siltstone under cyclic loading. Int J Rock Mech Min Sci 2024; 174:105645.

[32] Yue WT, Feng XJ, Wang EY, Zhao EL, Wang DM, Liu QL, et al. Signal response and energy evolution of separated sandstone. Phys Fluids 2025; 37(2):024107.

[33] Li ST, Chen XD, Zhang JH. Acoustic emission characteristics in deterioration behavior of dam concrete under post—peak cyclic test. Constr Build Mater 2021; 292:123324.

[34] Du K, Bi RY, Sun Y, Yang CZ, Wang SY, Li GC, et al. Failure behaviors of granitic rocks induced by point/local loads under biaxial compression stress state. Acta Geotech 2023; 18(9):4645—69.

[35] Ohno K, Ohtsu M. Crack classification in concrete based on acoustic emission. Constr Build Mater 2010; 24(12):2339—46.

[36] Zhu J, Deng JH, Chen F, Wang F. Failure analysis of water—bearing rock under direct tension using acoustic emission. Eng Geol 2022; 299:106541.

[37] Zhang ZH, Deng JH. A new method for determining the crack classification criterion in acoustic emission parameter analysis. Int J Rock Mech Min Sci 2020; 130:104323.

[38] 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.

[39] Dong LJ, Zhang LY, Liu HN, Du K, Liu XL. Acoustic emission b—value characteristics of granite under true triaxial stress. Mathematics 2022; 10(3):451.

[40] Xia CG, Chen DL, He W, Liu HN, Liu XL. Research on maximum likelihood b—value and confidence limits estimation in doubly truncated apparent frequency—amplitude distribution in rock acoustic emission tests. Mathematics 2022; 10(14):2409.

[41] Shang XY, Lu YY, Li B, Peng K. A novel method for estimating acoustic emission b—value using improved magnitudes. IEEE Sens J 2021; 21(15):16701-8.

[42] Gao RB, Xie HP, Wu F, Li CB, Ye CF, Liu Y. Deep learning—enhanced acoustic emission localization for damage evolution analysis in coal—concrete composite structures under cyclic loading. Eng Struct 2025; 343:121208.

[43] Shui X, Zhou L, Zhu ZM, Nie FK, Wang HH, Zhang HD. Investigation of the fracture characteristics of mixed—mode I/III crack by using two kinds of sandstone specimens. Eng Fract Mech 2024; 310:110488.

[44] Yue WT, Wang EY, Feng XJ, Tan TJ, Zhang L, Chen D, et al. Homogeneity—dependent fracture behavior and instability mechanism of composite coal—rock: Insights from three—point bending tests. Int J Min Sci Technol 2025; 35(6):913-32.

[45] Zha ES, Zhang R, Zhang ZT, Ai T, Ren L, Zhang ZP, et al. Acoustic emission characteristics and damage evolution of rock under different loading modes. Energies 2020; 13(14):3649.

[46] Zhuang WT, Li SH, Deng Q, Chen M, Yu QL. Effects of coarse aggregates size on dynamic characteristics of ultra—high performance concrete: Towards enhanced impact resistance. Constr Build Mater 2024; 411:134524.

[47] Wu QH, Yang Y, Zhang KX, Li YJ, Chen W, Liu ZF. Uniaxial compression mechanical properties and deterioration mechanism of sandstone under different humidity conditions. J Cent South Univ 2023; 30(12):4252—67.

[48] Li XL, Liu ZT, Feng XJ, Zhang HJ, Feng JJ. Effects of acid sulfate and chloride ion on the pore structure and mechanical properties of sandstone under dynamic loading. Rock Mech Rock Eng 2021; 54:6105—21.

[49] Zhou QL, Liu DP, Lin XD. Pre—evaluation of fault stability for underground mining based on geomechanical fault—slip analysis. Geomat Nat Hazards Risk 2022;13(1):400-13.

[50] Kong P, Jiang LS, Shu JM, Wang L. Mining stress distribution and fault—slip behavior: a case study of fault—influenced longwall coal mining. Energies 2019; 12(13):2494.