Abstract
The thermal stability of the surrounding rock is pivotal to the efficient and safe production of high-temperature fluidized mining engineering. To investigate the thermal stability of rocks, this paper takes the roof sandstone of Tongxin coal mine as the research subject and tests the changes in various physical properties such as mass, size, wave velocity, porosity, and permeability with temperature. Additionally, thermal analysis testing and microscopic observations were conducted. The analysis yielded the following conclusions: (1) The thermal stability of the surrounding rock is pivotal to the efficient and safe production of high-temperature fluidized mining engineering; (2) The alterations in Tongxin sandstone's physical properties primarily stem from dehydration, thermal stress, quartz phase transitions, and kaolinite dehydroxylation. (3) The analysis of the pyrolysis process can predict the evolution rules and threshold temperature of various physical parameters efficiently; (4) a model that links wave velocity and permeability in sandstone at different temperature has been formulated, predicated on the interrelation of physical properties; (5) Based on the evolution rules of various physical properties and the analysis of the pyrolysis process, along with microscopic observation results, the evolution rules and mechanisms of the internal structure of Tongxin sandstone after heating were obtained.