## 1 Introduction  
The Yulong Copper Mine in Tibet, China, is 4569-5118 m above sea level. The mining area is a semi-arid alpine region with a continental climate, and has rich and reliable copper resources. This region mainly adopts a strip mining method. In the process of resource development, the rock slope of the strip mine in such high-altitude and cold regions is exposed for a long time, and there are cracks, weak interlayers, stratification, and other structural surfaces (Figure 1). Under rainfall and groundwater conditions, the fissures will gather water to form a frozen rock mass. In the process of mineral resource development, a frozen rock mass is often encountered. In order to carry out safe and efficient engineering and mining, a deep understanding of the mechanical properties of frozen rock mass is of crucial guiding significance for improving the development efficiency of open-pit mineral resources and construction safety and prevention of accidents in high altitude cold regions [1; 2; 3; 4; 5; 6; 7]. The tensile strength, compressive strength and shear strength of rock are important indicators for measuring the physical and mechanical properties of rock. The damage and failure of rock are usually controlled by the tensile strength. There are two main methods to test the tensile strength of rock, the first is direct stretching, and the second is indirect stretching. However, the direct tensile test requires specific laboratory equipment and complex operations, and the indirect tensile test has a more mature theoretical system. So, the indirect tensile test, namely the Brazilian splitting test, is generally used to test the tensile strength of rock [8; 9]. Many scholars [10; 11; 12; 13] have analyzed the changes of tensile strength, tensile sensitivity coefficient, radial strain, AE energy accumulation and release, crack initiation and fracture mode of rock specimens through the Brazilian splitting laboratory test and numerical simulation. Their research considered the prefabricated fissures, pores, different strain rates, degrees of water saturation, different particle sizes, different angles, high temperatures, filling of fissures, and other factors. At present, there are mature theoretical systems and methods for reference. The research on low-temperature rock mechanics mainly focuses on the mechanical properties of frozen intact rock [14; 15; 16; 17] and the influence of the freeze-thaw cycle on the failure characteristics of the rock's mechanical properties [18; 19; 20; 21]. The mechanical properties of frozen intact rock are mainly determined by freezing temperature, initial water content and loading rate. [PERSON] et al. [22] studied the mechanical properties of various rocks under dry or saturated conditions through uniaxial compression and Brazilian splitting tests. The results showed that the compressive and tensile strength and elastic modulus increased significantly at \(-160\)\({}^{\circ}\)C, and the compressive and tensile strength and elastic modulus varied according to the type of rock and the degree of water saturation. [PERSON] et al. [23] studied the mechanical properties of sandstone at low temperatures through uniaxial and triaxial experiments. They found that the tensile and compressive strength of rock increased with the decrease in temperature. Still, the elastic modulus was less affected by temperature in the section from \(-10\) to \(-20\)\({}^{\circ}\)C. [PERSON] et al., [PERSON] et al., [PERSON] et al., and [PERSON] et al. [24; 25; 26; 27] studied the mechanical properties of a variety of rocks under negative temperature through uniaxial and triaxial experiments. The results showed that the compressive strength, internal friction angle, cohesion force and elastic modulus of the rocks all increased with the decrease in temperature. They attributed the increase in mechanical properties with decreasing temperature to the shrinkage of mineral particles at low temperatures, the increased strength of the ice itself, and the interaction of the frost swelling force with the rock.