## 1 Introduction  
With the large-scale construction of infrastructure such as high-speed railways, highways, and water conveyance tunnels in the western region of China, tunnel projects in the gullied and ridge-hilly areas of the Loess Plateau face numerous challenges. The unique structural and water-sensitive characteristics of loess often lead to engineering disasters during tunnel construction, including surface subsidence, large deformations of the surrounding rock, sudden water intrushes, mud flows, lining cracks, and water leakage [1; 2; 3]. These pose significant safety challenges to tunnel construction in water-rich loess geological conditions. In response to the series of engineering problems faced during the construction and operation of loess tunnels, many researchers have conducted systematic research and analysis from aspects such as the causes of the problems, disaster mechanisms, prevention measures, and more. [PERSON] [4] used the surrounding rock grade, groundwater conditions, burial depth, excavation method, and support closure time as risk factors. Through the deep mining of the existing case data, he established a collapse analysis and prediction model for loess tunnels. This model predicts and analyzes the impact of various risk factors on the construction of loess tunnels. Based on mathematical theory, [PERSON] [5] established a model for identifying and analyzing the risk of collapse in loess tunnels. This model examines and analyzes the impact weights of multiple factors such as the surrounding rock lithology, terrain, excavation span, burial depth, groundwater, rainfall, construction technology, and management level on the risk of collapse in loess tunnels. It provides a new method for evaluating the risk of collapse during the construction of loess tunnels. Based on the existing research findings, [PERSON] [6] conducted a systematic analysis of 27 typical loess tunnels in loess regions. They proposed that the main types of water-rich loess surrounding rock are naturally water-rich, excavation-induced water enrichment, and surface rainfall infiltration-induced water enrichment. They elaborated on the formation mechanism and seepage characteristics of water-rich surrounding rock, providing valuable references for the theoretical research, design, and construction of loess tunnel projects. [PERSON] [7] conducted research and analysis on the impact of spatial distribution changes in soft plastic loess on large-section high-speed railway tunnels through on-site monitoring and measurement. The results indicate that different spatial positions of the soft plastic loess layer relative to the tunnel will lead to different mechanical behaviors during tunnel construction. [PERSON] [8] comprehensively considered factors such as loess structural evolution, shear deformation zone distribution, excavation face instability, geological conditions, surrounding rock damage, and support structures. Through numerical analysis, they revealed the formation mechanisms of different types of failure during the construction of loess tunnels. This provides a reference for the prevention and treatment of engineering disasters in loess tunnel projects. Through field investigations, [PERSON] [9] conducted an in-depth study on the causes and evolution mechanisms of loess collapse dolines, providing effective techniques for erosion control in loess tunnels. [PERSON] [10] and others addressed the issue of roof collapse during the construction of the Bailuyuan Tunnel. They analyzed the causes of the collapse and proposed treatment measures, such as grouting at the tunnel face and advanced pipe roof support. The effectiveness of these measures was verified through in situ monitoring and numerical analysis. [PERSON] [11], taking a specific tunnel as an example, aimed to resolve various engineering disasters occurring when tunnels pass through water-rich loess strata. By using base grouting and curtain grouting, they effectively controlled surrounding rock deformation and surface subsidence.