Investigation of the Effect of Modeling of Control Tunnel in Retaining Structure of J2 Station of Mashhad Metro Using Plaxis 2D

Nowadays using of underground concrete arch excavation method is very common for execution of retaining structures (soldier structure) of deep and semi deep metro stations all around the world. In this method executer can use retaining structure as a part of main structure of station in next construction steps with using of piles of retaining structure as a part of main structure\u27s wall. One of the first steps in building retaining structure of metro station is control tunnel (patrol tunnel) that usually is a prefabricated controlling tunnel in the middle of retaining structure. This tunnel is used for digging bores for concrete piles and arches of retaining structure and will be removed at the end of excavation process. Usually designers don\u27t consider this tunnel in modeling of whole retaining structures in numerical modeling in computer programs like PLAXIS. We have done 2 different modeling of retaining structure of J2 station in Mashhad metro (with and without control tunnel) for considering of the impact of modeling of control tunnel on stresses, deflections, axial forces, bending moments, etc of the model using PLAXIS 8.5 2D. Results and differences between these two kinds of modeling showed that neglecting the patrol tunnel in analyses can cause important reductions in forces and moments of piles and ribs of the retaining structure