The stabilization of a slope-viaduct system without closing traffic

ABSTRACT A case history concerned with the stabilisation of a slope-viaduct system is reported. The two-carriageway viaduct was built 39 years ago on a rather gentle slope that did not show any sign of instability. In 2010 a landslide took place and damaged the viaduct. As the relocation of the motorway was deemed unpracticable, the alternative solution of stabilising the slope and repairing the viaduct was chosen. The owner asked to design remedial measures that did not require the closure of the viaduct. This was possible since the movements of the slided mass were slow and regular. The slope-viaduct system was stabilised by improving, firstly, the bearing conditions of the decks, then strengthening the existing foundations of the involved piers, and finally stabilising the slope by reducing the pore water pressure by means of subhorizontal drains. The remedial works were successfully carried out and resulted to be effective.