Evaluation method of multi-factor coupled large deformation grading under high geo-stress conditions: taking Wangjiagou Tunnel as an example

To accurately analyze the risk of large deformation of tunnels under high geo-stress, a new multi-factor coupled prediction method for large deformation classification and evaluation is proposed, which comprehensively considers formation age, small angle influence coefficient, rock strength, rock layer thickness, rock mass integrity, and in-situ stress. Taking the Wangjiagou Tunnel project as an example, a true three-dimensional model is established and numerical simulation methods are used to invert and analyze the in-situ stress, thereby obtaining the maximum normal stress values at each tunnel mileage. According to the new method, the geological risk of the Wangjiagou Tunnel is mainly characterized by large deformation risk, with Class Ⅰ large deformation being predominant (1155 m, accounting for 21.62%), followed by Class Ⅱ large deformation (130m, accounting for 2.43%). Further comparison with the single strength stress ratio method has verified that the evaluation results based on the multi-factor coupled method are closer to the actual working conditions, indicating that the new evaluation method is more applicable and can provide theoretical support and a scientific basis for the safty design and construction of the Wangjiagou Tunnel project.