Consolidation of platforms

Since May 2017 the Design and Construction Joint Venture has completed backfilling operations to reclaim land from the sea. But backfill material must be set up and settled before the ferry terminal and related infrastructures are built.

Taking into account the filling material height and the hydraulic transport of sand, compacting with traditional mechanical means such as a roller hydraulic compactor, was not possible.

For this crucial step, several solutions to accelerate settlement were thus studied and implemented by the Design and Construction Joint Venture :

  • The static compaction by overloading backfilled area with more material weight during several months with measurements by means of a compaction gauge during this period.
  • The dynamic compaction consisting in compacting either with the fall (between 7 and 30 m) of heavy loads (between 8 and 35 tons) or with the vibro flotation process. This latest solution mainly used on Calais Port 2015 site consists in pushing a needle into the backfill material while injecting water then raising it step by step by vibrating. The grains of sand thus rearrange by compacting mechanically.