integrated fuzzy ahp- topsis for selecting the optimal tunnelling method

tunnelling method selection is one of the most crucial decisions that should be made by tunnelling engineers. compatibility of a selected tunnelling method with the geological and geotechnical conditions is crucial to success of a tunnelling project. on the other hand, selecting the proper tunnelling method is a multi-criteria decisionmaking (mcdm) problem with regard to many geological and geotechnical variables and uncertainties and also unpredictable ground conditions during tunneling operation. this paper develops an evaluation model based on the analytic hierarchy process (ahp) and the technique for order performance by similarity to ideal solution (topsis), to help the engineers in tunnelling industries for the selection of optimal tunnelling methods in a fuzzy environment. the fuzzy-ahp is used to determine global weights of the criteria and fuzzy topsis method is used to obtain final rankig of alternatives. this approach is applied to select optimal tunnelling method among six tunnelling techniques including open tbm, double shield tbm, single shield tbm, roadheader, drilling & blasting and hydraulic hammer in cham-shir water conveyance tunnel of iran. finally, single shield tbm was selected as optimal tunnelling method in cham-shir water conveyance tunnel of iran.