Probabilistic Stability Analysis of Tunnel No.2 of Kurdistan, NW Iran

Stability analysis of tunnels is a geotechnical engineering problem characterized by many sources of uncertainty. Therefore, rock characteristics could not be defined by deterministic values and probabilistic methods would be as a suitable alternative. The tunnel No.2 of Kurdistan in NW Iran is a road tunnel and a part of tunnel is composed of shale rocks. To use probabilistic analysis, the best fitted distributions to rock mass characteristics were first obtained. Using point estimate method (PEM) method we combine probabilistic input variables such as deformation modulus and intact uniaxial compressive strength, and evaluate the distribution of the output variables such as total displacement. The obtain results show that probabilistic approach, when it is possible to have sufficient data on the quality of the rock mass, leads to a better understanding of the project risks.