(Technical Note) Selection of TBM Type in Tunnels with Diverse Geological Conditions, Case Study of Motevaselian Tunnel

Selecting a suitable tunnel boring machine is one of the most important issues in mechanized tunneling in urban environments. Factors such as geological and geotechnical conditions of the tunnel route, groundwater condition, costs, technical and environmental factors are important factors affecting the selection of TBM in urban tunnels. The Motevaselian tunnel with a length about 10 km is located along the Sayyad Highway from the north of the Sepah Sq. to Azadegan highway. Due to the north-south direction of the tunnel route, in terms of geological and geological conditions, there are a wide variety of geological units. According to the geological conditions, the tunnel route is divided into three parts: north, middle and south, which have different conditions for TBM selection. This has caused some complexities in the choice of TBM type. In this paper, it is tried to investigate geological and geotechnical conditions and also consider other factors affecting the operation of tunneling machines and then to propose the most suitable TBM for tunneling based on the methods and guidelines for selection of the machine. Therefore, using multivariate decision making criteria, analyzes in different scenarios were performed. For the whole tunnel route, in addition to the geotechnical aspects, regarding the cost factor and environmental-technical factors, EPB machine was selected slightly well than Slurry machine.