Stability Analysis of a Tunnel in Hydrostatic Conditions Using Different Reliability Methods in @Risk and RT Software

One way to stability analysis of tunnel is to examine the convergence and radius of the plastic zone around it. On the other hand, uncertainties in the design parameters lead to the evaluation of the safety of structures using probabilistic and reliability methods. In this research was presented a methodology for stability analysis of two tunnels (under different conditions), by Hock-Brown and Mohr-Coulomb theory using robust reliability methods including: first order method (FORM), second order method (SORM) and Monte Carlo simulation in new RT and @Risk software. After probabilistic modeling in these two software, the results of the analysis show that the second order reliability method is more accurate than the first order method in more complex limit state functions. Also, at high values ​​of failure probability, first order and Monte Carlo simulation methods provide more realistic outputs and at low values ​​of failure probability, Monte Carlo simulation method is not recommended.In addition, the tunnel without pressure has a high probability of failure (24%), so that providing a support with 0.12 MPa pressure is efficient.