## 1 Introduction  
Diebe Gorman & Co. developed the first artificial ground freezing (AGF) in Swansea, South Wales, UK, in 1862. The technique was mainly used to sink underground coal mines [1]. In 1883, the German mining engineer [PERSON] improved the system and patented it [2]. Due to its reliability, the AGF method was chosen in the construction of a 50-meter-deep shaft in a fully saturated sandstone structure [3]. Since then, the system has been used extensively as a temporary ground support system. In contrast to other geotechnical support methods, AGF is not restricted to specific project sizes or ground types. For example, it can be used in small-scale projects such as the in-situ sampling of Pleistocene sands [1, 4] as well as in large-scale projects such as underground uranium mines [5, 6]. Apart from the use of AGF in fine-grained sands such as slit sand and clay sand [7], the method can also be applied to fractured sedimentary rocks such as sandstones [8]. Additionally, as AGF is a temporary process, it has a minimal environmental impact, and no foreign substances, such as cement or chemical grouting, are added to the ground. Once the AGF process is completed, ground thawing occurs, thereby returning the formation to its original state. The main disadvantage of AGF systems is the substantial operational costs and energy consumption [9, 10]. As a consequence, several studies have been conducted to evaluate and enhance the AGF process [5, 11, 12, 13, 14]. At the same time, many scholars have conducted a lot of research on the use of AGF as a method for reinforcing contact channels. [PERSON] et al. [15] established a three-dimensional thermos lid coupling model using ANSYS to study the construction development characteristics of the artificial freezing method in water-rich sand layers and derived the distribution law of the temperature diffusion in the ground. [PERSON] et al. [16] analyzed the construction monitoring results in conjunction with the construction of an extra-long connection aisle in Nanjing. They achieved the development of a frozen wall when two shield tunnels were frozen at the same time and obtained the timing of its excavation. [PERSON] et al. [17] introduced the construction process with thawing and sinking grouting of the No. 6 contact channel of a Jinan metro interval and analyzed the surface settlement monitoring results of the freezing method during the construction. It was found that the critical period for the surface and underground pipeline settlement was 5 days before thawing, and the forced thawing measures could effectively control the thawing and sinking phenomenon within a short period of time. [PERSON] et al. [18] analyzed the evolution of a permafrost curtain according to a three-dimensional finite element numerical model of a section of the Nanning metro and observed that the distribution of temperature diffusion in the stratum was regular. Many scholars have studied the laws of temperature field distribution during the freezing process [18; 19; 20; 21; 22; 23; 24]. Hohhot is the capital of the Inner Mongolia Autonomous Region and is located at the intersection of the Eurasian Continental Bridge, the Yellow River Basin Economic Belt, and the Bohai Sea Economic Circle. With complex geological conditions and soil types, it is an important city in northern China's frontier region. Presently, numerical simulation methods are used to investigate the development of the temperature field of the connection aisle freezing method during construction. Most of the research content is focused on the physical properties of the soil, freezing tube setting parameters, and external factors of the connection aisle; however, there have been limited studies on artificial freezing methods and the impact of the freezing process on brine cooling plans.