ABSTRACT
This paper describes the main design and execution criteria for peripheral earth retaining solutions required to construct a multi-family residential building on Avenida Conde Valbom in Lisbon. The building covers approximately 200m², encompassing three underground and seven elevated floors. The excavation area is bordered by a 10-floor building with one underground level to the north and an 8-floor building with five underground stories to the south. Geological findings indicate a groundwater level of around 4 meters. Soil investigations reveal clayey fill materials, rocky fragments, and other elements atop dark gray clays, followed by Miocene formations named “argilas e cálcarios dos prazeres” and “Formação de Benfica” from the Eocene-Oligocene era. For excavation and containment, the proposed method involves utilizing the “king post wall” technique horizontally supported by a slab strip. This approach includes phased construction of vertically reinforced concrete panels, supported by micro-piles. The slab strip provides load-bearing support and incorporates HEB140 double shorings where necessary. This solution permits a thinner wall (0.30m) and simultaneous execution during excavation. To ensure stability against soil pressures during excavation, concrete pouring of panels directly into the ground is planned, with support from the slab strip and metallic shorings at existing floor levels. Monitoring and survey plan aims to execute excavation and containment structures safely and economically while assessing the behavior of neighbouring structures during construction. It addresses identified constraints and quantifies risks associated with the construction phase.
