Study on Seismic Damage Risk Assessment of Mountain Tunnel Based on the Extension Theory

In this paper, the extension method is applied to the assessment of seismic damage risk in mountain tunnels. Based on various considerations such as the geological conditions of the tunnel site, the state of the tunnel, the structural situation and the earthquake, the seismic damage risk assessment index for mountainous tunnels is proposed. The range of values of different assessment indexes under each grade is quantified. The seismic damage risk of the tunnel is divided into four classes, and assessed based on the extension theory. The specific assessment process is as follows: Firstly, five tunnels affected by the Wenchuan earthquake were selected to construct the matter element to be assessed, and construct the classical domain and nodal domain; then, the entropy weight method and analytical hierarchy process (AHP) were used to determine the weights of each index; finally, the correlation function values were calculated to obtain the seismic damage risk level of the tunnels. Among them, the seismic damage risk level of the Longchi tunnel and Longxi tunnel is “high risk”, and the seismic damage risk level of the Longdongzi tunnel, Youyi tunnel and Maanshi tunnel is “moderate risk”. The five tunnels are sorted according to the eigenvalues of the seismic damage risk level as follows: Longchi tunnel > Longxi tunnel > Longdongzi tunnel > Youyi tunnel > Maanshi tunnel. Combined with the seismic damage investigation of the Wenchuan earthquake, the actual seismic damage of tunnel is consistent with the assessment results, which verifies the accuracy and effectiveness of this method. The seismic damage risk assessment model for mountain tunnels proposed in this paper has certain reference value for the future seismic damage risk assessment of tunnels.