Investigation of Tunnel Face Support Pressure Effects on the Aqueduct Using Numerical Modeling (Case Study Tabriz Metro Line 2)

In urban environments, due to the existence of structures in the city such as buildings and, more importantly, the presence of people in them, as well as existing underground structures such as service spaces including sewage tunnels, aqueducts, and adjacent tunnels, there have been always concerned about damages to these structures and their interactions existed as a result of tunneling. Significant interaction effects can occur when a new tunnel is dug in the vicinity of an existing tunnel. For example, the construction of a new tunnel could impose unauthorized deformations or bending moments on the existing structural support system. This interaction depends on parameters such as the distance of the tunnels, the size of both tunnels, the rigidity of the support system and the method used to locate the second tunnel, and the geotechnical characteristics of the excavation site.Aqueducts are underground structures and excavating new tunnels can have special interaction effects on these structures. An aqueduct is a subterranean canal with a gentle slope, which connects water-rich zones at high altitudes to the fields where cultivation takes place.According to studies, the interaction between underground structures is one of the critical factors that affect ground displacement and subsidence. The effect of the interaction between the tunnels as well as the amount of face pressure on the ground subsidence has been investigated using methods such as physical modelling, numerical modelling, and local measurements. In this paper, the effect of face pressure has been investigated in excavating the 2nd tunnel Line of Tabriz Metro on existing aqueducts. It is worth noting that for 3D modelling, FLAC3D software is used in this paper.