Optimum Design of a Shallow-Buried Urban Metro Station Using the Diaphragm Wall Construction Method

With progress in the field of civil construction projects especially in geotechnic projects, various construction methods have been introduced to fulfill project purposes. Underground structures and deep excavations, as essential part of construction of main structure, are also of advancing projects. Applying various construction methods is contingent on the possibility of achieving a suitable and correct design method. In some cases it is needed to combine different construction methods to reach a suitable design. This article studies a three-storey shallow-buried urban metro station using diaphragm wall construction method. Some of the challenges in this study are the slab-wall connection type and the geometry of the bottom slab (foundation), as a flat or arch slab, and concluding an optimum design. In this study the analysis is based on finite element method. In a similar state of slab-wall connection the structure is analyzed under two conditions: flat and arch bottom slab; and analysis results are compared and contrasted. The internal forces and moments in the structural members are then compared in static and seismic analysis. By studying the analysis results, slab geometry and connection type are chosen according to the internal forces and structural behavior. The analysis showed that in the structure with arch bottom slab the internal forces (moment and shear) in the wall especially in the first floor are greater compared to that of the structure with flat bottom slab. Moreover, the analyses and study of connection types indicted that the optimum design is reached when the connection of floor slabs to the wall is of fixed type and the connection of invert to the wall are pinned.