Changes in b-values due to sandstone failure after exposure to high temperatures

To better investigate the effect of high temperatures on the b -values of acoustic emissions (AEs), the fracturing of sandstone when subjected to uniaxial compression testing after different heat treatments is monitored by examining the AEs. The results show that the b -values are rapidly reduced around the yield stress and reduce to the lowest value at the peak stress during the loading process. After 550°C, the b -value of the yield stress of sandstone begins to decrease with temperature increases. On the other hand, there is a rapid increase in the b -value when the temperature is 700°C. The changes in the b -values mainly depend on the loading stress and thermal damage to the quartz particles or the boundaries of the quartz particles and other minerals (especially at around 573°C, which corresponds to the phase transition of quartz in the sandstone). The research results of this paper have important guiding significance for geotechnical engineering under high-temperature conditions, which can be used for rock stability monitoring and disaster early warning.