Soils Improvement by PVD in a Harbor Storage Area

Abstract

In the south bank of the Tagus River, in the Lisbon harbor, it was necessary to create a large raw mineral storage area for a steel plant adjacent to it, as well as a new quay for discharge of those materials, some years ago. The occurring formations in the area included very soft soils layers, up to 17 m thick. The inherent geotechnical problems to the development were of two types: those soils did not have enough strength to support a walking man, least the storage piles, without a substantial improvement of their strength; and the equipment used, on rail, to move the raw minerals could not be submitted to differential settlements greater than 15 cm, over 500 m. The total area of the storage facility to improve was 25 ha. This paper introduces the comparison between the monitoring data of the experimental embankment built on top of the soil improved area by PVD with a recent 3D modelling of the stresses evolution. A special attention is given to the behavior, under loading, of the soft soils foundation, especially by comparing it with the first results of the trial embankment.