Study On Damage Evolution And Constitutive Model Of Cemented Backfill During Deformation

Under the background of the industrial civilization turning to ecological civilization,the construction of green mines has risen to the national strategy.Green mining technology is the source of green mine construction.The filling mining method has been paid more and more attention because of its safety and high efficiency.The cemented backfill is used as an artificial pillar in the two-step mining.Its stability is the guarantee for safe and efficient mining of mines..Therefore,it is urgent to carry out the damage evolution and constitutive model research of the cemented backfill deformation process,which provides a theoretical basis for the stability monitoring and control of cemented backfill.In this paper,through the uniaxial compression test of cemented filling body,using ultrasonic testing and acoustic emission monitoring technology,using damage mechanics and statistical related theoretical knowledge,combined with numerical simulation method and indoor similar simulation test,the damage evolution of cemented backfill deformation process is carried out.And constitutive model research,the following main research results have been obtained:(1)Through the ultrasonic wave velocity test of cemented backfill,it is found that there is an exponential relationship between the uniaxial compressive strength and the elastic modulus of the cemented backfill and the ultrasonic wave velocity.Combined with the damage mechanics theory,the damage evolution of the cemented backfill is constructed based on the ultrasonic wave velocity.The equation quantitatively characterizes the damage evolution law of cemented backfill.(2)The cracking observation,crack propagation,propagation and penetration mode of cemented backfill were studied by using the camera system.The crack cracking,expansion and penetration mode of the cemented body during deformation were studied.The number of cracks was obtained by colorimetric method,and the whole process of cemented backfill deformation was discussed.The relationship between the number of cracks and the ultrasonic wave velocity.(3)According to the ringing count rate and energy rate phase characteristics,the whole process of deformation is divided into three periods: rising period,calm period and active period;the rising sound emission parameters are active,the calm period is in the energy storage period,and the active period sounds.The "jumping" increase of the emission parameters;combined with the spatial location of the microcracks and the timing characteristics of the acoustic emission parameters,the damage variables are defined based on the acoustic emission parameters,and the spatial evolution mechanism of microcracks inside the cemented backfill is discussed.(4)According to the periodic characteristics of the stress-strain curve of the cemented backfill under uniaxial compression and the nonlinear deformation characteristics of the initial compaction stage,the damage constitutive model of the cemented backfill is constructed and combined with the FLAC3 D numerical simulation software.Based on the sub-development,the damage constitutive numerical model of cemented backfill based on FLAC3 D was obtained.The correctness of the damage constitutive model was verified by similar simulation experiments.