## 1 Introduction  
Although the open excavation method was widely used in the past, its limitations have become more apparent as the demand for underground space in urban areas continues to grow. Issues such as long construction periods, low efficiency, and significant environmental impact have become important factors restricting the progress of underground space development. As a result, vertical shaft construction technology has gradually developed towards higher automation, less construction disturbance, and smarter, information-driven methods. New construction methods, such as the pneumatic caisson, the press-in caisson, the SOCS (super open caisson system) developed by Japan, and VSM (vertical shaft sinking machine) developed by [PERSON] in Germany, have emerged and are gradually replacing open excavation. The pneumatic caisson creates an air pressure environment higher than the external water pressure to ensure a water-free working environment inside the caisson, which is suitable for an underwater tunnel and foundation construction [1]. However, it is difficult to maintain stable air pressure in practice, and the equipment is complex. The SOCS combines unmanned underwater excavators with electric hydraulic grabs, significantly improving the construction efficiency in hard strata [2], and has been used in over 11 cases in Japan. The press-in caisson method pushes the caisson into the ground mechanically, offering high stability [3; 4], but it faces issues like sudden sinking or delayed sinking in weak strata [5; 6]. The VSM technology controls shaft sinking through suspension sinking. The shaft is made of prefabricated concrete segments, and mechanical arms cut and crush the surrounding soil while mixing it with water and pumping it out for secondary treatment. This method is widely used around the world [7; 8; 9; 10]. Additionally, China has proposed SBM [11; 12; 13] and CTM [14] methods, based on the VSM technology, which are highly mechanized and involve less human intervention, further advancing innovation in vertical shaft construction technology. For shafts constructed using the VSM technology, [PERSON] et al. [15], based on a sewage treatment project in Singapore, compared the settlement of VSM with traditional shafts and concluded that VSM causes less disturbance to the soil and provides higher economic benefits compared to traditional methods. [PERSON] et al. [16] analyzed an underground intelligent parking garage project in Nanjing and investigated the force and structural response patterns of the VSM sinking shaft wall during construction. [PERSON] et al. [17; 18] not only used numerical simulations to analyze the applicability of VSM in fine sand layers on the basis of the former, but also established a finite element simulation model based on a Shanghai pipeline project, revealing discrepancies between the traditional calculations of retaining walls and actual measurements. [PERSON] et al. [19] used both theoretical analysis and field data to conclude that the VSM structure is highly applicable in soft soil areas. [PERSON] et al. [20] compared the differences among the theoretical calculations, field measurements, and numerical simulation results, and concluded that the risk of bottom hole inrush is small during the excavation of the VSM. Based on a certain underground parking garage in Shanghai, [PERSON] et al. [21] proposed a design to reinforce the base slab beam, effectively reducing about 50% of the convergence deformation. [PERSON] et al. [22] further analyzed the interaction between piles and soil, finding that increasing the pile diameter by 20% increases the bearing capacity by 15% and reduces the soil settlement by 12%. It can be observed that these scholars focus on the analysis of vertical shaft construction techniques and the structural response during shaft sinking, but research on the impact of the VSM technology on the surrounding soil layers is relatively limited.