Damage evolution of rock-encased-backfill structure under stepwise cyclic triaxial loading  

作　　者：Xin Yu Yuye Tan Weidong Song John Kemeny Shengwen Qi Bowen Zheng Songfeng Guo 

机构地区：[1]Key Laboratory of Shale Gas and Geoengineering,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing,100089,China [2]Innovation Academy for Earth Science,Chinese Academy of Sciences,Beijing,100089,China [3]University of Chinese Academy of Sciences,Beijing,100049,China [4]School of Civil and Resources Engineering,University of Science and Technology Beijing,Beijing,100083,China [5]Key Laboratory of High-Efficient Mining and Safety of Metal Mines(Ministry of Education of China),University of Science and Technology Beijing,Beijing,100083,China [6]Department of Mining and Geological Engineering,University of Arizona,Tucson,AZ,86721,USA

出　　处：《Journal of Rock Mechanics and Geotechnical Engineering》2024年第2期597-615,共19页岩石力学与岩土工程学报（英文版）

基　　金：We acknowledge the funding support from the National Natural Science Foundation of China Youth Fund(Grant No.52004019);the National Natural Science Foundation of China(Grant No.41825018);China Postdoctoral Science Foundation(Grant No.2023M733481).

摘　　要：Rock-encased-backfill(RB)structures are common in underground mining,for example in the cut-andfill and stoping methods.To understand the effects of cyclic excavation and blasting activities on the damage of these RB structures,a series of triaxial stepwise-increasing-amplitude cyclic loading experiments was conducted with cylindrical RB specimens(rock on outside,backfill on inside)with different volume fractions of rock(VF=0.48,0.61,0.73,and 0.84),confining pressures(0,6,9,and 12 MPa),and cyclic loading rates(200,300,400,and 500 N/s).The damage evolution and meso-crack formation during the cyclic tests were analyzed with results from stress-strain hysteresis loops,acoustic emission events,and post-failure X-ray 3D fracture morphology.The results showed significant differences between cyclic and monotonic loadings of RB specimens,particularly with regard to the generation of shear microcracks,the development of stress memory and strain hardening,and the contact forces and associated friction that develops along the rock-backfill interface.One important finding is that as a function of the number of cycles,the elastic strain increases linearly and the dissipated energy increases exponentially.Also,compared with monotonic loading,the cyclic strain hardening characteristics are more sensitive to rising confining pressures during the initial compaction stage.Another finding is that compared with monotonic loading,more shear microcracks are generated during every reloading stage,but these microcracks tend to be dispersed and lessen the likelihood of large shear fracture formation.The transition from elastic to plastic behavior varies depending on the parameters of each test(confinement,volume fraction,and cyclic rate),and an interesting finding was that the transformation to plastic behavior is significantly lower under the conditions of 0.73 rock volume fraction,400 N/s cyclic loading rate,and 9 MPa confinement.All the findings have important practical implications on the ability of backfill to support underground ex

关 键 词：Rock and backfill Triaxial cyclic loading Volume fraction Damage evolution 3D visualization 

分 类 号：TU43[建筑科学—岩土工程]