Study Of Infrasound Signal Characteristics Of Red Sandstone Before And After The Peak Stress Under Uniaxial Loading

As one of uniaxial loading member underground mining process,a pillar often turn out to be deformation or instability under axial stress,so studying the process of internal instability or deformation characteristic change,has a certain theoretical and engineering significance.Compared to limitations of traditional acoustic emission technology,this paper puts forward a infrasonic signal detection means based on the infrasonic wave.In order to simulate acoustic emission signal characteristics of the underground pillar deformation or instability process at the axial stress,and related laboratory rock infrasound experiment is carried out.The data of the mechanics and infrasound signal are collected when the red sandstone is loaded under uniaxial loading conditions,the infrasound signal characteristics of rock samples is analyzed before and after the peak stress,and obtained the main following conclusions:1.For analysis on characteristics of stress-infrasound time domain signal,the obvious infrasound signal is presented before and after the peak stress,and there have different degrees quiet period.For progressive failure of rock sample,infrasound signal amplitude after peak stress in the overall level will be also have apparent performance,before the different degree of stress level fall,are accompanied by intense infrasound signal generally.For brittle fracture failure of rock samples,before the peak stress,there is a obvious infrasound signal appears,and then the acoustic signal amplitude level of red sandstone infrasound signal appear a certain degree of decline after the peak stress until the overall destruction.2.For analysis on time-frequency characteristics of rock samples,the characteristic of damage frequency of red sandstone is concentrated in the range of 1 ~ 4Hz,the time-frequency characteristics reflects the similar characteristics of time domain signal before and after the peak stress.3.For analysis on accumulative ring down count characteristics of stress-infrasound of red sandstone sample,the increment of accumulative ring down count of infrasound signal is very noticeable in the previous peak stress under brittle failure,after its peak stress until the rock sample overall damage is fewer than the previous peak stress.For progressive failure of rock sample,the performance of accumulative ring down count of infrasound signal is also apparent,before the different degree of stress level fall,usually incremental of accumulative ring down count will have a relatively clear upward trend.4.For analysis on energy rate of rock sample stress-infrasound signal,the higher levels energy rate of infrasound signal of red sandstone is appeared before the peak stress,and energy rate of infrasound signal is relatively low at the peak stress,and have different degrees of quiet period before peak stress.For brittle fracture failure of rock sample,energy rate of infrasound signal is increased in the process of macroscopic fracture surface formation,but the overall level of infrasound energy rate is decreased significantly than previous peak stress.For progressive rock sample damage,before the different degree of stress level fall,are accompanied by high rate of energy levels of infrasound signal appears generally.