Selection of a subway support system With Multi Criteria Decision Making Method

When the tunnel passes through the weak and different soil conditions, the soil between the tunnel and the surface of the ground move. And the development of these movements to the surface of the ground will be accompanied with the subsidence of the surface structures. Therefore in order to do necessary planning to create supports considering the conditions of the location of doing the project, providing a decision making model is essential in choosing an appropriate option for tunnel supports in planning phase and designing the tunnel project. The aim of this paper is to offer a useful design to specify and choose suitable options for Karaj subway tunnel supports, as a good model for later stages use. This pattern is formed on the basis of technical, financial, administrating, social and effective factors on the site of doing the project by noticing a variety of criteria. The final goal is selecting the most suitable option aimed all the probable options for choosing subway tunnel supports system and noticing effective and important criteria on which basis and by using multi-criteria decision making and new research methods during the operation, proper options are prioritize and ultimately the best ones are chosen. In AHP and TOPSIS methods, alternative (D) NATM method is selected as the best alternative for support system. On the other hand the results taken by numerical modeling with PLAXIS software shown that alternative D is the best support system with 26mm displacement and 10mm subsidence in the section.