| The cemented tailings backfill in the maintenance stage is susceptible to disturbance caused by ground pressure and result in instability.The failure process can be characterized by Acoustic Emission(AE)parameters and the complex fracture morphology can be quantified by fractal dimension.In view of these phenomena,the physical parameters determination tests,uniaxial compression experiment,AE monitoring test and fracture scanning test were conducted on the cemented tailings backfill with cement-tailing ratio of 1:6 of Chengchao Iron Mine with curing times of 3d,7d,14 d,21d,28 d,35d,42 d,50d,60 d,80d,100 d,120d,150 d,200d and 300 d to analyze the physical and mechanical properties,AE characteristics during uniaxial compression,the fractal characteristics of fracture,and the relationship between each other of cemented tailings backfill at different ages.The results can provide reference for the strength design and the stability monitoring of cemented tailings backfill which has certain reference and engineering application value.The results are shown as follows:The physical and mechanical properties of cemented tailings backfill with different ages of Chengchao Iron Mine.The density and moisture content of the backfill increase rapidly from 3d to 42 d and tend to be stable from 42 d to 300 d.The velocity of P-wave,uniaxial compressive strength and deformation modulus increase with age between 3d and 120 d,while the Poisson's ratio decrease with age from 3d to 120 d and remain stable between 120 d and 300 d.The uniaxial compressive strength of the 42-day cemented tailings backfill can account for 88% of the long-age strength of the CTB,therefore,the 42 d can be used as the basis for recovery of subsequent mining adjacent to cemented tailings backfill.The deformation process of the cemented tailings backfill with different ages can be divided into compaction stage,micro-rupture initiation to stable expansion stage,progressive rupture stage and post-rupture stage.AE characteristics of cemented tailings backfill with different ages of Chengchao Iron Mine during the uniaxial compression process.The acoustic wave of backfill with age of 3d and 7d is rarely.In the range of 14 d to 42 d age,as the age increases,the AE wave,the ring count and AE energy increase gradually during the uniaxial compression of the cemented tailings backfill The change of the AE parameters of cemented tailings backfill from 42 d to 300 d is similar.Compared with the progressive rupture stage,the compaction stage,the initiation of the micro-rupture to the stable expansion stage and the post-failure stage,the ring count and the AE energy are smaller.During the progressive rupture stage,the oscillating period and the quiet period appear,combing which as the precursor can better predict the instability of the cemented tailings backfill..Fractal characteristics of fracture of cemented tailings backfill with different curing ages of Chengchao Iron Mine.The fracture of the cemented tailings backfill with different ages of Chengchao Iron Mine has good self similarity and the fractal scaleless range is 4.4~11.0?m.the fractal dimension of fracture of the backfill gradually increases in the range of 3d to 120 d and tends to be stable from 120 d to 300 d.The relationship between AE characteristics and fractal characteristics of fracture of cemented tailings backfill with different curing ages.The AE characteristics and fractal characteristics of fracture is closely related to the physical and mechanical properties,which reflect the AE characteristics and fractal characteristics of fracture are affected by the physical and mechanical properties.The total AE ring count and the total AE energy decrease linearly with the fractal dimension,which demonstrate the more energy the cemented tailings backfill release,the smaller the fractal dimension and roughness of the fracture morphology are.The fracture morphology of the cemented tailings backfill contains information related to AE characteristics... |
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