Abstract: Understanding the dynamic behavior and instability characteristics of coal at different temperatures can provide reference for rock mechanics problems in coal mining, underground coal gasification, and other engineering projects. Based on the Hopkinson compression bar experimental system, uniaxial dynamic failure mechanics experiments of coal samples were conducted to study the influence of different temperatures on the dynamic behavior of deep coal samples. The mechanical characteristics, failure mechanisms, and energy evolution laws of coal samples were analyzed from the perspectives of macro and micro failure states and energy dissipation. The research results indicate that there is a quadratic relationship between the temperature of coal samples and the mass loss rate, and as the temperature increases, the mass loss rate increases. The dynamic strength of coal samples shows a trend of first increasing and then decreasing with the increase of temperature, with the maximum mechanical strength of coal samples at 100℃. The dynamic elastic modulus of coal samples decreases linearly with increasing temperature. The fragmentation of coal samples at different temperatures is mainly composed of fragments, particles, and coal particles. The average particle size of coal samples shows a trend of first increasing and then decreasing with the increase of temperature, while the fractal dimension shows a trend of first decreasing and then increasing with the increase of temperature. The failure mode transitions from axial splitting failure at low temperatures to compressive shear splitting composite failure at high temperatures. Using scanning electron microscopy (SEM) to observe the coal sample, it was found that before heating, the coal sample was mainly composed of micropores and microcracks. Before 100℃, the cracks in the coal sample gradually closed due to the thermal expansion of coal particles, resulting in an increase in mechanical strength; Continuing to heat up, the number of mesopores and transition pores begins to increase, the crack width widens, the number increases, and the mechanical strength decreases. Under the premise of considering temperature, analyze the trend of changes in the incidence rate, reflectivity, and transmittance of energy. The research results help to reveal the formation mechanism of deep mine dynamic disasters and provide theoretical basis for the prevention and control of mine dynamic disasters under high temperature conditions.
 

Temperature; Coal; Impact; Dynamics; destroy