Subway Stations Retaining Walls: Case Histories in Soft and Hard Soils

In the last twenty years, sixteen pile-supported metro stations have been built in Buenos Aires in a wide range of geotechnical conditions. After an initial design of the construction procedures including partial open-trench (in two cases), all subsequent fourteen stations were excavated employing cut&cover techniques. In all cases, vertical bored piles were employed both to support the lateral ground pressure and the loads acting on the roof slab. This paper revisits the geotechnical conditions in Buenos Aires City, describes the procedures employed for the design and numerical analysis of pile-supported excavations and presents the behavior of five recent cases located in widely different geotechnical profiles. The paper ends with a summary of lessons learned which are relevant both for design and construction.