Study On The Relationship Between Strain And Acoustic Emission Characteristics During Creep Of Red Sandstone

Rock creep exists widely in all kinds of underground engineering,It will be conducive to the monitoring of the stability of engineering to study on acoustic emission characteristics of rock creep.Based on the creep test of red sandstone on acoustic emission.Firstly,the relationship between the strain rate of rock and acoustic emission under creep was studied.and the acoustic emission was employed to characterize damage on the process of rock creep.Then,the relationship between the damage and the strain was discussed by means of the strain percentage and the acoustic emission parameters.Finally,the relationship between strain and acoustic emission was analysed on the uniaxial compression state.Studying on the rock damage process under two stress paths,the acoustic emission criterion which was suitable for the creep damage was founded.The main conclusions are as follows:(1)In the process of red sandstone creep failure,the rate of acoustic emission parameters increases with the increase of strain rate.And the acoustic emission ringing counts-time curve and creep strain-time curves were similar.To a certain extent,the damage process of rock can be characterized by acoustic emission parameters.(2)In the red sandstone creep damage process,with the increase of strain rate,the main frequency of acoustic emission was increased,the range of the main frequency band was wider.main frequency mainly keep between 100~350kHz in the constant creep stage;Entering the acceleration creep stage,the maximum frequency was 500 kHz,the band of main frequency remained in the range of 75~450kHz It showed that on the accelerated creep stage,the initiation of the new crack and the formation of the macro crack were synchronous.(3)The red sandstone creep failure had similar strain and acoustic emission characteristics under different strain rate.(4)There was no obvious linear relationship between the strain rate and acoustic emission amplitude or acoustic emission amplitude events rate under red sandstone uniaxial compression.With strain increase the acoustic emission events rate increased steadily.When the strain reached a certain range,the acoustic emission events rate began to increase significantly until the rock failure.However,the strain rate was linearly related to the acoustic emission amplitude and acoustic emission events rate under red sandstone creep process,With strain increase the acoustic emission events rate was fluctuant,and there were many "sudden increase" in the acoustic emission events rate before the rock failure.(5)The relationship between the strain and acoustic emission events rate and relationship between the strain rate and acoustic emission amplitude or acoustic emission events rate can be used to determine the state of rock creep.