Mechanical behaviors of backfill-rock composites: Physical shear test and back-analysis  

作　　者：Jie Xin Quan Jiang Fengqiang Gong Lang Liu Chang Liu Qiang Liu Yao Yang Pengfei Chen 

机构地区：[1]State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,430071,China [2]University of Chinese Academy of Sciences,Beijing,100049,China [3]School of Civil Engineering,Southeast University,Nanjing,211189,China [4]Energy School,Xi’an University of Science and Technology,Xi’an,710054,China

出　　处：《Journal of Rock Mechanics and Geotechnical Engineering》2024年第3期807-827,共21页岩石力学与岩土工程学报（英文版）

摘　　要：The shear behavior of backfill-rock composites is crucial for mine safety and the management of surface subsidence.For exposing the shear failure mechanism of backfill-rock composites,we conducted shear tests on backfill-rock composites under three constant normal loads,compared with the unfilled rock.To investigate the macro-and meso-failure characteristics of the samples in the shear tests,the cracking behavior of samples was recorded by a high-speed camera and acoustic emission monitoring.In parallel with the experimental test,the numerical models of backfill-rock composites and unfilled rock were established using the discrete element method to analyze the continuous-discontinuous shearing process.Based on the damage mechanics and statistics,a novel shear constitutive model was proposed to describe mechanical behavior.The results show that backfill-rock composites had a special bimodal phenomenon of shearing load-deformation curve,i.e.the first shearing peak corresponded to rock break and the second shearing peak induced by the broken of aeolian sand-cement/fly ash paste backfill.Moreover,the shearing characteristic curves of the backfill-rock composites could be roughly divided into four stages,i.e.the shear failure of the specimens experienced:stage I:stress concentration;stage II:crack propagation;stage III:crack coalescence;stage IV:shearing friction.The numerical simulation shows that the existence of aeolian sand-cement/fly ash paste backfill inevitably altered the coalescence type and failure mode of the specimens and had a strengthening effect on the shear strength of backfillrock composites.Based on damage mechanics and statistics,a shear constitutive model was proposed to describe the shear fracture characteristics of specimens,especially the bimodal phenomenon.Finally,the micro-and meso-mechanisms of shear failure were discussed by combining the micro-test and numerical results.The research can advance the better understanding of the shear behavior of backfill-rock composites and contribute to the

关 键 词：Physical simulation Backfill-rock composites Shear failure CRACKING Shear constitutive model 

分 类 号：TU52[建筑科学—建筑技术科学]