ABSTRACT
The Metro Line 4 is the new underground line under construction in Milan, connecting the east to the west of the city centre. The underground Dateo station is one of the boldest along the whole line. Its depth is the maximum never reached by the subway lines built in Milan and it is determined by the exigency to pass under the existing underground Bovisa-Dateo Railway Link. The excavation is 31 m deep, 20 m below the water table, 60 m long and 23 m wide, having a distance from adjacent buildings less than 3 m. Retaining structures consists of 50 m high concrete diaphragms, 1.20m thick, with a 20 m injected bottom plug. It was excavated using a combined bottom-up/top-down method. The paper focuses on two key aspects of the design: settlement control of the nearby existing buildings and construction countermeasures to avoid drainage and counteract high underground water pressure.
