ABSTRACT
As part of the extension of the Yellow and Green lines of the Lisbon Subway, the underground alignment of lot 2 starts at Santos Station and runs southwards ending at the terminal of the Cais do Sodré Station. The design of a new underground station – Santos Station has been considerably demanding. The highly complex geological and geotechnical challenges and the constraints related to surface occupation in a densely populated part of the city, where ground movement assessment is paramount, played a significant role in the selection of available design options for enabling the shaft and tunnelling works of the station. The geological and geotechnical challenging conditions are expressed by highly complex multi-layered terrain with formations of diverse nature such as Made Ground, Miocene formation, the upper cretaceous Lisbon Volcanic Complex, and the underlying Cretaceous formation. The scope of the article is to provide an insight of the achievements made by means of the design tool that has been adopted for the assessment of the stress and strain conditions of the surrounding ground due to the shaft and tunnelling construction works, as well as the assessment of forces and displacements on the primary support, enabling the carrying-out of stability checks and design optimization. As such, for this purpose, 3D FE models (Plaxis 3D 2022.01) have been developed. The ground and groundwater conditions, the constitutive modelling of ground behaviour, the structure-ground-structure interaction and the construction sequence of the shaft and tunnelling works have been comprehensively considered in these analyses.
