Experimental Study On The Multivariate Information Characteristics Of Acoustic Emission Dominant-frequency In Tunnel Rock Burst

With the increasing of mining depth,rthe engineering disasters are increasing,and rock burst has become one of the main problems which threaten the safety of engineering.Therefore,the containing hole granite as the experimental model,develop the condition of different loading rates,confining pressure and water rock burst acoustic emission experiment and debris microscopic fracture scanning experiments.From the rock crack initiation,accumulation and development before rock burst,extract the highest frequency,the lowest frequency,the sensitive dominant-frequency rate and dominant-frequency coefficient of variation from dominant-frequency.Study rockburst dominant-frequency multiple precursor information characteristics and rock burst debris micro fracture mechanism,and on this basis of multi frequency information of rock burst precursory characteristics.The main conclusions are as follows:1)The highest frequency,the lowest frequency,the sensitivity frequency rate and frequency coefficient of variation were extracted from the full waveform dominant frequency as acoustic emission multivariate information,which was compared with small scale crack initiation,big scale crack initiation,crack accumulation and crack development,the stage characteristics is obvious,and the physical meaning is clear.2)Under different influence factors on rock burst multiple precursor information characteristics of acoustic emission dominant-frequency are as follows: with increase of loading rate,the highest frequency 90~110k Hz signal number decreased,the lowest frequency 10~25k Hz signal number increased;The sensitive frequency rate and dominant-frequency coefficient of variation mutation point ahead;With increasing of confining pressure,the high frequency 90~110k Hz signal number decreased,the lowest frequency 10~25k Hz signal number increased,the sensitive frequency rate and the frequency of the coefficient of variation in violent period of time lag;When filled with water granite highest frequency 90~110k Hz number were reduced,low frequency of 10~25k Hz and 0~1k Hz signal number increased.3)The relationship of acoustic emission dominant-frequency multiple information characteristics and rockburst microscopic fracture characteristics are as follows: the number of the highest frequency 90~110k Hz band signal increases with the increase of the tensile component of rock burst,the number of the lowest frequency 10~25k Hz and 0~1k Hz band signal increase with the increase of the shear component of rock burst;with the increasing of the wear crystal cracks proportion,the sensitive frequency rate and the frequency of the coefficient of variation in violent period of time lag in the condition of constant loading rate.4)The lowest frequency,sensitivity frequency rate and frequency coefficient of variation are proposed as the main parameters,the highest frequency as the auxiliary parameters,developed multi parameter joint monitoring,to carry out "data acquisition","data processing","precursor identification" and "classification warning" four steps rockburst early warning method.The results provide a new method and basis for the application of acoustic emission in the monitoring and warning of the rock burst disaster.