ABSTRACT
The construction of the three connecting tunnels between the east side and the west side of the Centrum Nauki Kopernik underground train station, adjacent to the Vistula river, has a long and complex history, as they cross beneath one of Warsaw’s main road arteries (Wislostrada). After the attempt to excavate the first tunnel, the face of the tunnel collapsed on the night of August 13, 2012, and a volume of about 10,000 cubic meters of liquid mass (water, silty soil and sand) entered and flooded the west side of the station, which was filled with more than seven meters of material. Fortunately, the workers managed to escape, but machines and equipment were lost. This paper deals with how the tunnels were completed, by adopting soil improvement, jet grouting, GRP bars, ground freezing and a careful choice of work steps.
