Risk Assessment of Water Inrush for Underwater Tunnel Based on GT Combination Weighting and Interval Extension Theory

To achieve the accurate prediction of the dynamic risk of water and mud inrush during underwater tunnel construction, a two-stage risk assessment theory and methodology of water and mud inrush based on game theory combination weighting and interval extension theory is proposed, comprising preliminary and secondary assessments. Due to the uncertainty of geological and hydrological conditions and the uncontrollability of construction factors, a ternary fuzzy interval number rather than a fixed value is used to quantify the evaluation index of water inrush. The correlation functions in extension theory are improved. A game-theory-based combination weighting model is constructed by considering the subjective weight of the improved AHP and the objective weight of the FCM. The proposed method is applied to evaluate the water inrush risk of the river-crossing section in the Yuelongmen Tunnel from the Chengdu–Lanzhou Railway. The results show that the risk level of water inrush at the river-crossing section is high, and the evaluation results of the proposed method are consistent with the actual situation. It has been proven that the method is effective and scientific, and it is more suitable for identifying the risk of water inrush in complex geological conditions.