Research Article

Tunnel Probabilistic Structural Analysis Using the FORM

Table 4

Results of the reliability analysis of tunnel stability, considering the joints strength parameters (C, φ, Ten) as the independent random variables (scenario 2).

Block code (BC)FORM analysisMonte-Carlo simulation
Reliability index ()Probability of failure () %Calculation time (sec)Function iterationsIterations (~needed)Probability of failure () %Simulation time (sec) (~needed)Actual

0 0 0
0 0 13.8386.19 × 10−310.658~1.62 × 106N-A~2.82 × 105N-A
0 1 010.3202.76 × 10−239.457~6.61 × 1026N-A~1.15 × 1026N-A
1 0 11.5695.88.55220005.53480.093
1 1 02.0212.179.75250002.018900.099
1 1 10.06647.410.66760047.5104.90.043

: calculation (simulation) time using a 2.67 GHz, core i5 processor.
: it is not possible to calculate in reasonable time period with ordinary processing units.