Locating the portal of Moshampa dam diversion tunnelsusing AHP approac

Location of tunnel portal is always one of the vital concerns of geotechnical engineers and inappropriate selection of its position on financial conditions and the time the project will have significant impact. Locating the tunnels portal depends on different technical parameters (such as ecstatic and dynamic safety factor, hardness and position of relaxation pool) and financial factors (time, Maintenance, lining and soil stripping costs). In many situations, there are some proposed sites with different parameters, and it is necessary that the optimum tunnel portal location be selected with the help of multi-criteria decision making methods.In this paper, we have first studied the tunnel portal site selection criteria and their effects on the selection of the location of the tunnel portal. Then, using the Analytic Hierarchy Process (AHP) method, the decision making problem was hierarchically structured at three levels. To check the practicality of the method, the appropriate site for diversion tunnel portal was selected at Moshampa dam, Zanjan province, Iran.