Research on dynamic fuzzy prediction method for surrounding rock stability of mountain tunnels throughout the construction period

The factors influencing the stability of the surrounding rock are complex and diverse, characterized by fuzziness and variability. This leads to continuous changes in the stability state of the surrounding rock during tunnel construction, posing a significant threat to construction safety. This paper proposes a dynamic fuzzy prediction method for the stability of surrounding rock throughout the entire construction period of mountain tunnels. Firstly, considering deformation, engineering, and geological factors, a stability evaluation system for the surrounding rock is established, comprising 3 primary indicators and 21 secondary indicators, with the stability state of the surrounding rock classified into five levels. Each evaluation indicator is quantitatively characterized throughout the entire construction period based on the specific of different construction stages. In this process, by defining traction points and traction control equations, an intelligent time-series prediction model for surrounding rock deformation based on traction correction is proposed to accurately obtain surrounding rock deformation indicators. Additionally, a combination weighting method based on the Analytic Hierarchy Process (AHP) and the Entropy Weight Method (EWM) is introduced to calculate the combined weight values of each evaluation indicator at key construction nodes. Simultaneously, a strategy for dynamically adjusting indicator weights is proposed. By defining a weight dynamic adjustment equation, the weights of indicators are smoothly adjusted during different construction periods, achieving real-time updating of indicator weights throughout the entire construction period. The accuracy and reliability of this method are validated through the case study of the Jingang Tunnel, and reasonable suggestions for subsequent construction are provided. This method enables stability prediction and evaluation of surrounding rock throughout the entire construction period, offering a new approach for risk assessment in tunnel construction.