## 2 Research Status of TBM Risk Assessment  
[PERSON] used the fuzzy analytic hierarchy process to evaluate potential risks such as unstable surrounding rock, water influx, and collapse encountered during TBM excavation [9]. GU identified key risk factors in TBM construction and evaluated tunneling risks using the fuzzy comprehensive risk assessment method with entropy weight. The risks were mainly divided into equipment risk, excavation risk, and auxiliary construction risk based on engineering characteristics, further subdivided into more specific basic risks [10]. SI analyzed major geological issues encountered in deep-buried water diversion tunnel TBM construction and evaluated them based on indicators such as surrounding rock stability, high ground stress, and groundwater conditions [11]. LIU selected excavation parameters and rock mass parameters as evaluation indicators for coal mine tunnel TBM construction to assess the tunability of the tunnel and adaptability of TBM excavation layers [12]. WEN conducted a risk assessment for jamming caused by collapses during TBM excavation; they studied the relationship between torque and resistance moments of excavation parameters, established a probability calculation formula for jamming based on probability theory, and then evaluated the risk of the TBM cutterhead according to probability levels [13]. LIN assessed the occurrence of jams in TBM construction through interpretation structure models and Bayesian networks; they analyzed factors such as the surrounding rock grade, fault zones, and groundwater conditions that contribute to TBMs getting stuck using posterior probability analysis [14]. [PERSON] studied the risks generated when TBMs pass through squeezing formations during construction; they conducted simulation studies using extensive data to analyze the adaptability of TBMs to various geological conditions, and nonlinear regression equations were established based on excavation parameters for evaluation purposes [15]. [PERSON] adopted a linear elastic-viscoplastic constitutive model based on Perzyna overstress theory, which considered the time dependence of plastic deformation through a single viscous parameter [16]. [PERSON] analyzed the maximum shear stress of surrounding rock and finally obtained the variation law of displacement and shear stress of surrounding rock with different deterioration degrees and different dip angles [17]. Based on field evaluation and numerical analysis, [PERSON] proposed risk control countermeasures such as TBM driving parameter control, sand and gravel backfill, backfill grouting, and bottom grouting [18]. According to the aforementioned studies, it is evident that different studies place varying emphasis on indicator selection for different types of risks in TBM construction risk assessment. These disparities primarily stem from the diverse and intricate nature of the geological conditions, engineering environment, equipment performance, and construction technology involved in TBM construction. However, fully identifying these risks throughout the entire construction process often proves challenging. The risks associated with tunneling using a TBM is a dynamic issue wherein different risk factors may arise during various stages of construction or changes in surrounding rock types at the excavation face. For instance, during excavation, particular attention must be given to geological conditions and the safety performance of TBM equipment. Geological conditions can be influenced by numerous factors such as underground rock formation stability and groundwater conditions, which impact both the safety and efficiency of construction operations. Simultaneously, inherent risks are also present within TBM equipment itself; equipment failure or misoperation can lead to severe accidents. Therefore, it becomes imperative to systematically decompose risks layer by layer throughout each phase of the project when dealing with tunneling using a TBM.