Abstract:
It is of great significance to carry out the research on rock high temperature damage information identification for geothermal development and underground coal gasification. Based on the changes of acoustic emission parameters RA and AF in the failure process of sandstone after different high temperature treatments, the development and evolution law of different types of cracks in sandstone after high temperature treatment are studied. The results show that tensile cracks are dominant in the whole loading process of sandstone. When the loading stress exceeds 80% of the peak stress, the proportion of shear cracks increases rapidly, which can be regarded as the precursor of sandstone failure. When the heating temperature exceeds 600℃, the proportion of shear cracks increases. When temperature exceeds 800℃, the proportion of shear cracks decreases rapidly. Therefore, 600℃ and 800℃ can be regarded as the threshold temperature of sandstone damage mutation. After high temperature treatment, the dislocation pileup phenomenon increases, the plastic characteristics of sandstone strengthen, and the proportion of tensile cracks increases. The research results will provide an important theoretical basis for the identification of precursor information of rock fracture and instability after high temperature treatent.