Lisbon new circular Metro line: Buildings underpinning

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Publication Title
Lisbon new circular Metro line: Buildings underpinning

Abstract
The new Lisbon circular metro line will crosses a densely urbanized part of the city, connecting Rato Station located at one of the hills of the city and Cais do Sodré Station, at the Tagus River right bank. The underground excavation intersects a wide range of materials, from rock mass to soft soils. Where the construction of the tunnel section is closer to the river, with about 10 m of cover, a Cut&Cover method is used. In this metro the tunnel intersected a pile foundation of two reinforced concrete buildings with 9 upper floors and 1 basement, determining the need to underpin the structures and change permanently its foundation system. The geotechnical and geological conditions present in this metro, associated to highly limited access and working conditions, led to the execution of the retaining walls using jet-grouting technology. Those elements were also used as the building deep foundations, which consists of a reinforced concrete slab (length=50m, width=13m and thicknesses=1.4m and 1.8m), being also responsible for the structure underpinning. In this complex process is defined a controlled load transfer between the structure and the new slab, which was executed using hydraulic jacks, limiting the building differential settlements thought gradual jacks opening and according with monitoring. This paper presents an overall description of the solutions, how they were implemented and the buildings' behaviour during the underground works.
Authors
C. Martins; Catarina Fartaria; R. Tomasio; Alexandre Pinto

Published In

18th European Conference on Soil Mechanics and Geotechnical Engineering (ECSMGE2024)

Theme

D - Current and new construction methods

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