## 1 Introduction  
Thermal shock phenomena are commonly found in the field of science and technology. For example, geothermal development, thermal rock breaking, high-temperature overwater tunnel construction, nuclear waste disposal, etc. Therefore, rock thermal shock has received a lot of attention. Rock thermal shock is a phenomenon in which a large amount of heat exchange occurs in a short time when a rock is sharply heated or cooled, and the temperature dramatically changes, creating a huge temperature gradient inside the rock [1; 2]. Rocks are a typical porous media material, and the mineral crystals that make up the rock have different lattice energies and thermal expansion coefficients. As the degree of thermal shock increases, the thermal shock velocity increases, the intermolecular binding force decreases, and the thermal stress of the shock exceeds the destructive strength of the rock [3; 4; 5; 6]. The rock will generate a large number of fractures and cracks from the micro and fine levels, promoting the connectivity of the fracture network. This leads to changes in physical and mechanical properties such as bulk density, compressive strength, and tensile strength [7; 8]. These variations are complex, and are different for different rock types [9]. Therefore, the study of the evolution of physical and mechanical properties of rocks under the effect of thermal shock is of great significance for the in-depth understanding and development of high-temperature rock mechanics. Many researchers have performed extensive studies on high-temperature rock mechanics, including porosity and longitudinal wave velocity [10; 11; 12], static properties [13; 14; 15; 16; 17], kinetic properties [18], and the intrinsic connection between physical and mechanical properties and microstructural changes of different types of rocks [19]. The temperature conditions under which the above conclusions were obtained are real-time high temperature or after high temperature. In recent years, due to the urgent engineering needs, the damage characteristics of rocks after thermal shock action have received wide attention. Some scholars have analyzed the physical and mechanical characteristics and evolution laws of granite under thermal impact by combining mechanical tests with theoretical studies. It is believed that the cooling rate during thermal shock can have a large effect on the mechanical properties of the rock [20; 21; 22]. In order to explore the damage mechanism of granite by high temperature and thermal shock, respectively, relevant experimental analysis was conducted, and it was pointed out that the mechanical strength deterioration of granite after thermal shock treatment was higher [23; 24; 25]. Similar patterns have been found for other types of rocks [26; 27]. It can be seen that most of the studies around the evolution law of physical and mechanical properties of rocks under the action of temperature are focused on real-time high temperature or after the action of high temperature, and the study under the action of thermal shock needs to be deepened. Limestone is a carbonate rock with calcite as its main component, which is an important industrial raw material. It is also one of the most widely distributed minerals in the Earth's crust [18]. The southeastern region of China is located at the southeastern edge of the Eurasian continent. The geological and tectonic movements are intense, forming hydrothermal geothermal resources with abundant reserves [28]. Most of the thermal reservoirs in this area are sedimentary rock formations dominated by limestone. In the development of geothermal resources in the region, thermal shock action can increase the permeability of limestone reservoirs, promote the construction of artificial thermal storage, and improve the efficiency of heat extraction. It can also protect the stability of the drilling envelope by controlling the reduction of limestone thermal shock rupture.