Study Of Creep Acoustic Emission Characteristics Of Red Sandstone Under Different Loading Paths

In order to study acoustic emission characteristics of rock creep damage under different loading paths.First,a creep damage model of rock based on acoustic emission was built.Secondly,creep experiment of red sandstone under step loading and step loading and unloading were carried out,on the basis of experiment,The failure process of rock creep damage is discussed and studied from the acoustic emission signal parameters,focuses on the rock in different should stress level of creep process of acoustic emission amplitude,acoustic emission event rate,acoustic emission ring count rate,cumulative acoustic emission event and cumulative acoustic emission ringing count characteristic;Finally,the acoustic emission of rock creep damage variable model has been demonstrated and studied The main conclusions are as follows:1)To describe the micro mechanics the parameters statistical methods and the Weibull distribution function were used.The creep damage variable model was built based on rock acoustic emission.2)Analyzing the acoustic emission characteristics of the creep process under different loading paths,the creep damage mechanism of rock is revealed.The results show that: The acoustic emission in the high stress level has the characteristics of low frequency and high intensity than in the low stress level.3)Rock creep under step loading and step loading and unloading,the changes law of acoustic emission parameters are consistent in the first few levels of stress in the creep process.But in the last stress level.the acoustic emission parameters are change small and in a relatively calm state and sudden increase in the accelerated creep stage under the step loading creep condition;the acoustic emission parameters will appear short "surge" then leveled off before the acceleration creep stage,in the accelerated creep stage acoustic emission signal are increasing under the step loading and unloading creep condition.4)In the same stress level,the acoustic emission parameters of step loading and unloading creep process variation frequency was obvious higher than that of step loading creep process.5)The creep damage evolution law of rock under different loading paths can be well described by the acoustic emission of rock creep damage variable model.The proportion ofdamage variable is "U" shape with the increase the stress level both in the step loading creep and the step loading and unloading creep.But at the same stress level,the creep damage variable proportion of the step loading and unloading was obvious higher than that of step loading creep.