Analysis of Tunnel Reliability Based on Limit Strain Theory

Traditional analyses of tunnel reliability, which employ deformation values, such as surface settlement, crown settlement, and arch shoulder settlement, as instability indicators, fail to accurately depict the failure state of tunnel lining structures. In addressing tunnel instability induced by the failure of lining structures, the limit strain theory is introduced, designating shear strain penetration failure of the lining structure as the criterion for tunnel instability. A novel method for studying tunnel reliability, integrating neural network response surface methodology and Monte Carlo simulation, is proposed. The feasibility of the limit strain theory in reliability analysis is validated through the calculation of instability probabilities for specific tunnel projects, offering a fresh perspective on tunnel reliability assessment. Sensitivity analysis of rock mass parameters reveals that an increase in the variability of these parameters elevates the probability of tunnel instability and the shear strain value at the arch waists. Among these parameters, the variability of the modulus of elasticity (E) exerts the most significant impact on the probability of tunnel instability.