# Dynamic Risk Assessment of Ultra-Shallow-Buried and Large-Span Double-Arch Tunnel Construction
[29] analyzed the reasons for the inconsistency and proposed an improved AHP (IAHP), which they applied to subway construction risk identification. [PERSON] et al. [30] selected twelve factors affecting water inrush for the evaluation index system and used the fuzzy comprehensive assessment method to evaluate the water inrush risk of a karst tunnel. [PERSON] et al. [31] proposed a tunnel boring machine project delay risk assessment method based on Bayesian neural network. [PERSON] et al. [32] proposed a methodology for evaluating the important factor for the fire design of bridges. That proposed important factor was similar to those used to evaluate the wind and snow loads of buildings. [PERSON] et al. [33] determined important factors by comprehensively considering the concepts of hazard, exposure, and vulnerability. With the progress of society and the increasing complexity of engineering projects, the single assessment method often fails to obtain accurate assessment results. Consequently, risk assessment methods that combine two or more qualitative or quantitative analysis methods have gradually become popular. [PERSON] et al. [34] used the historical data of fifty tunnels and combined the fuzzy method with a neural network to establish a tunnel risk assessment model, which they then applied to the risk assessment of the Tiefodian tunnel. [PERSON] et al. [35] proposed a risk assessment model for coal mine flood emergency logistics by combining the AHP with a neural network. [PERSON] et al. [36] used the AHP method and fuzzy decision-making to evaluate the collapse risk of ridge tunnels. [PERSON] et al. [37] combined the interval FAHP with fuzzy cluster analysis to assess the flood risk of a subway system in a sinking environment. [PERSON] et al. combined the triangular fuzzy number (TFN) and the AHP into a geographic information system to assess the submergence risk of the Shenzhen subway system [38] and applied it to the evaluation of geological disasters [39]. Tunnel construction risk assessment is divided into static and dynamic risk assessments. Static risk analysis mainly focuses on the preliminary stage of the project, supporting a project feasibility study, the selection of construction methods, and the preparation of the project budget. In the construction process, the risks are evaluated and can change, and therefore the assessment results obtained by these models are often different from the actual situation. Therefore, the dynamic risk assessment of construction sites is necessary. [PERSON] [40] systematically introduced the principle of the dynamic risk analysis model based on the impact graph and DynRisk models of the Monte Carlo principle. At present, an increasing number of scholars are studying dynamic evaluation and have gradually studied dynamic methods after initially proposing the concept of dynamic evaluation. Currently, various methods can be used for specific and operable dynamic evaluation, and the dynamics are mainly achieved through four aspects: introduction of time and assignment of weight [41]; dynamic adjustment of the risk evaluation index system [42]; dynamic adjustment of the weights of risk evaluation indicators [43]; and division of the evaluation process into stages [44]. [PERSON] et al. [45; 46] established a dynamic collapse risk assessment method on the basis of the attributed comprehensive assessment model and evaluated the tunnel before excavation, after excavation, and before support. [PERSON] et al. [47] proposed a dynamic risk assessment method based on a Bayesian network in view of the shortcomings of the risk assessment of deeply buried tunnels. [PERSON] et al. [48] established a dynamic risk assessment system, including pre- and post-evaluation models, by using the attribute recognition model and performed risk analysis on sections in tunnels with a high risk of water inrush. Few studies have been conducted on the dynamic evaluation of urban underground engineering and fewer on the dynamic evaluation of urban shallow-buried and large-span double-arch tunnels.