Sduty On Acoustic Emission Characteristics Of Different Proportioning Backfill And Effect Of Layered Filling To Control Surrounding Rock

Based on the National Natural Fund Project?No.51764013?and Jiangxi Provincial Natural Science Youth Fund key project?No.20192ACBL21014?,this paper studies the layered filling and deformation mechanism of tantalum-niobium tailings cemented backfill in different filling spaces.Firstly,the mechanical and acoustic emission characteristics of specimens with different ash sand ratio of 1:4,1:8 and 1:10 were studied by RMT-150C loading system,PCI-? acoustic emission system and YJZ-16+strain acquisition system.The deformation characteristics and damage evolution law of specimens with different lime sand ratio and their combination during compression failure are discussed.The MATLAB software and G-P algorithm were used to process the acoustic emission data,and the fractal theory was used to analyze the correlation dimension evolution law of acoustic emission parameters of the specimens with different lime-sand ratio filling bodies during uniaxial compression failure,and the judgment basis of instability failure is obtained.Secondly,the deformation characteristics and acoustic emission characteristics of different proportioned filling body combination and rock and different proportioned filling body combination during uniaxial compression are studied.Finally,FLAC^3D numerical simulation software was used to carry out layered filling design analysis with different lime-sand ratios in different spatial sequences,and the optimal solution was obtained.Through the above research,the following conclusions are obtained:?1?The failure process of backfill under uniaxial compression is mainly divided into four different deformation stages:pore compaction stage,elastic stage,yield stage and failure stage,and the specimens with different lime sand ratio show different failure forms.The larger the lime-sand ratio of the backfill,the greater the uniaxial compression failure compressive strength.?2?Under uniaxial compression,the acoustic emission signals of the specimens with different ash sand ratio are less at the initial stage of loading,and the acoustic emission ring count and energy rate of the majority of the specimens appear at the early stage of elastic stage or yield stage.After the acoustic emission signal peak appears,it rapidly drops to the low level,accompanied by the "small peak" of the low level until the end of the test.?3?Under uniaxial compression failure,the acoustic emission parameter amplitude and energy rate of specimens with different lime-sand ratios have obvious fractal characteristics,and their associated fractal dimension changes have a certain similarity,which is generally expressed as:decline?rise?Down three stages.And at the peak stress level of about 30%to 60%,the frequency of the fractal dimension curve of acoustic emission is significantly higher than in other stages.In the range of 75%?90%of the peak stress level,the fractal dimension of amplitude and energy rate appears the process of maximum?minimum or sub maximum?minimum,and the specimen is in a critical state,which is the precursor of instability failure.?4?Under axial compression,the failure process of two kinds of specimens with different lime-sand ratios and rock-filled with different lime-sand ratios is mainly divided into four different deformation stages:the pore compaction stage,the elastic stage,the yield stage and the failure stage.And the larger the lime-sand ratio of the backfilling,the greater the compressive strength of the combined specimen.The average value of the acoustic emission ring count and energy rate of the composite specimen is the largest in the elastic stage.?5?The FLAC^3D software was used to build the numerical model,and six filling schemes are put forward,which are designed by three different spatial sequences with different lime sand ratios.Analyze the stability of surrounding rock and the deformation of the filling body,and finally determine the optimal combination ratio of scheme 6,divided into three layers,each layer is 10m,the upper layer filling ratio is 1:4,the middle layer filling ratio is 1:8,and the bottom layer filling ratio 1:10.