Experimental study on the effect of high temperature on the mechanical properties and acoustic emission characteristics of gritstone

摘要

In order to study the influence of high temperature on mechanical properties and acoustic emission characteristics of gritstone, X-ray diffraction, uniaxial compression and acoustic emission tests were carried out on the gritstone after the high temperature of 200?°C to 800?°C, and the effect mechanism of high temperature on the mineral composition, mechanical parameters and acoustic emission characteristics of the sample were analyzed. The results show that: The sample will gradually become brownish red with the increase of temperature. The damage mode of the sample exhibits shear tension composition damage. The direction of predominant fracture surface is the same as the loading direction for some samples, even with multiple secondary fracture. (2)With the increase of temperature, the content of SiO2decreases first and then increases, and it was the lowest at 400?°C. The diffraction intensity of crystal in the sample decreases first and it was the weakest at 400?°C, then shows an increasing trend, the critical temperature at 600?°C is about the crystallization of main minerals quartz. With the increase of temperature, the deformation modulus, the elastic modulus and the initial modulus all firstly decrease, then increase, and then decrease again, they all reached the maximum value at 400?°C. The peak strain increases first and then decreases as the temperature increases, reaching a maximum at 200?°C. During the uniaxial damage process, the accumulated ringing for acoustic emission of the sample covers three periods: The quiet period of acoustic emission, the slow rising period of acoustic emission and the sharp rising period of acoustic emission.