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

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外文摘要：Rock-encased-backfill(RB)structures are common in underground mining,for example in the cut-and-fill 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 experi-ments 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 be-tween 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 excavations.

外文关键词：

Rock and backfillTriaxial cyclic loadingVolume fractionDamage evolution3D visualization

作者：

Xin Yu、Yuye Tan、Weidong Song、John Kemeny、Shengwen Qi、Bowen Zheng、Songfeng Guo

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作者单位：

Key Laboratory of Shale Gas and Geoengineering,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing,100089,China

Innovation Academy for Earth Science,Chinese Academy of Sciences,Beijing,100089,China

University of Chinese Academy of Sciences,Beijing,100049,China

School of Civil and Resources Engineering,University of Science and Technology Beijing,Beijing,100083,China

Key Laboratory of High-Efficient Mining and Safety of Metal Mines(Ministry of Education of China),University of Science and

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

Department of Mining and Geological Engineering,University of Arizona,Tucson,AZ,86721,USA

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基金：

National Natural Science Foundation of China Youth FundNational Natural Science Foundation of ChinaChina Postdoctoral Science Foundation

项目编号：

52004019418250182023M733481

出版年：

2024

DOI：

10.1016/j.jrmge.2023.11.015

岩石力学与岩土工程学报(英文版)

中国科学院武汉岩土力学所中国岩石力学与工程学会武汉大学

岩石力学与岩土工程学报(英文版)

CSTPCD

影响因子：0.404

ISSN：1674-7755

年,卷(期)：2024.16(2)

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