Laboratory investigation of the temperature influence on the mechanical properties and fracture crack distribution of rock under uniaxial compression test

In order to study the influence of high temperature on the mechanical characteristics and crack distribution of progressive failure process of rock, the laboratory uniaxial compression experiments were carried out on sandstone treated with different temperatures (25–1000 °C), and the variation characteristics of stress, deformation, and acoustic emission parameters during the failure of samples were analyzed. At the same time, the fracture crack distribution and fractal characteristics were analyzed through the industrial computed tomography (CT) test of the failure samples. The results show that temperature can affect the deformation and strength characteristics of rock. The stress thresholds and elastic modulus appear to increase when the preheating temperature increases from 25 to 400 °C and decrease when greater than 400 °C. The activity of AE signal is positively correlated with temperature. The CT results confirmed that with increasing temperature, the fracture cracks in the failure samples changed from a small number of single fracture cracks to a complex and crisscross distribution of small cracks. The failure cracks gradually gathered in the middle of the samples. The box-counting dimension of the fracture crack is between 1.4060 and 1.7262, and higher preheating temperature corresponds to the larger box-counting dimension, indicating that the temperature increases the complexity of the fracture crack. This outcome shows that temperature has an important influence on the deformation and failure of rock.