## 1 Introduction  
The depletion of shallow coal resources results in a gradual increase in mining depth. Currently, deep mining encounters numerous engineering problems and technical challenges, including low mining efficiency, inadequate security measures, significant ecological damage, suboptimal resource recovery rate, and high energy loss [1]. Deep coal gasification mining is an efficient solution to these challenges, simultaneously mitigating the emission of pollutants during solid coal treatment and promoting the efficient and environmental utilization of coal [2, 3]. However, the high-temperature condition required in the gasification stop significantly affects the mechanical and physical properties of surrounding rocks, thereby exerting a substantial influence on mine stability [4, 5, 6, 7]. For example, under the influence of high temperatures, Carboniferous rocks, especially clay shales, lose their properties, their structure changes, and their strength and deformation parameters decrease [8]. Under high-intensity fluidized mining, the performance deterioration of surrounding rocks under the high temperature and strong disturbance results in frequent disasters of the surrounding rock, posing significant challenges for controlling and preventing instability and disasters in the surrounding rock [7; 9; 10]. Therefore, the investigation of the dynamic characteristics and fracture mechanisms of coal rock under high temperatures and impact loading is of great significance. The current research focuses on investigating the impact of elevated temperatures on the mechanical characteristics of rocks [11; 12; 13; 14; 15]. However, the research results exhibit significant variability, which can be ascribed to the intricate nature of mineral compositions and microstructures. At high temperatures, the original cracks, pores, and other microscopic structures in the rock are changed and rearranged. When the temperatures reach critical values, the mineral grains undergo physical and chemical transformations such as expansion, melting, and thermal decomposition, leading to variations in the mechanical properties of the rock mass [16; 17; 18; 19; 20; 21; 22]. The strong impact disturbance in the deep underground further exacerbates the challenge of the accurate evaluation of the complex mechanical characteristics of the rock mass under such a high-temperature environment. A series of advanced split Hopkinson pressure bar (SHPB) test systems, including confined pressure [23; 24] and static-dynamic combined loading control modules, have been designed to explore the mechanical characteristics of the rock mass under different stress conditions [25]. These research results are conducive to the safe development of deep coal resources [26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36; 37]. However, the superposition of temperature and stress in fluidized mining cannot be fully illustrated in the existing studies, and the coupling effect of temperature and stress on the mechanical characteristics of the rock mass during high-intensity fluidized mining still requires further investigation [6; 38; 39; 40; 41; 42; 43; 44] in the existing studies. It should be noted that dynamic mechanical characteristics of the rock mass in this special engineering are the result of the co-evolution of their internal crystal phases, pore structures, and stress fields under real-time high temperatures. Additionally, the melting or expansion of crystal phases at real-time high temperatures, as well as the formation of cracks induced by thermal stress, can further complicate the dynamic mechanical characteristics of the rock mass under external impact [45; 46; 47; 48].