Geotechnical Risks Assessment During the Second Part of Emamzadeh Hashem (AS) Tunnel Using FDAHP-PROMETHEE

Nowadays, the tunnels based on the public’s needs may be built in unfavorable geological conditions. In most of these situations, the use of mechanized excavation technology is unavoidable to improve the performance and safety. Mechanized tunneling in difficult conditions with many risks, including the fault zones, water inflow and squeezing that tunneling operations could stop for a long time. It is very important to predict and assess the hazards because of the large volume of investment in such projects. In this study, it was tried to investigate the stability and convergence of environment and water inflow in seven section of the second part of the Emamzadeh Hashem (AS) tunnel using analytical and numerical methods after identification of the geological characteristics and geotechnical risks. Then, the most risky section was investigated and introduced using Fuzzy Delphi Analytical Hierarchy Process (FDAHP) and PROMETHEE methods. Thus, after selecting criteria, including the instability of the tunnel, water inflow and squeezing, the weighting of each criterion was determined using FDAHP method according to the severity, rate and probability of disaster. Finally, the most risky section of the second part of Emamzadeh Hashem (AS) tunnel was evaluated using the PROMETHEE method. Thus the H-3 section was introduced and selected as the most risky section based on geotechnical properties. The results of this study showed that a combination of multiple criteria decision making, analytical, numerical and fuzzy methods can be used to predict and evaluate the geotechnical risks and doing disaster risk reducing actions to reduce the risk.