CRUX has examined the consequences of sand removal at the toe of the casing that is used for constructing the piles. The unwished effect while removing sand from this casing, which is placed on an inclined granite seabed, is that sand will wash in the casing, thus eventually reducing the stability of the seabed ‘foundation’ the Costa Concordia was laying on. Because neither the exact layout of the seabed, the thickness of the sand laying on top of it, nor the extent of the airlift outside the casing were known, FEM calculations were made to assess how far sand could be removed without the loss of the sand/soil stability.
CRUX also assisted in the feasibility study for permeation grouting the sand around the toe of the casing. In cooperation with the grouting contractors a special packer was developed in order to be able to grout from within the casing, thus stabilising the sand around the casing before drilling into the bedrock.
Because of the confidentiality agreement and the sensitive nature of the project, CRUX was only allowed to publish on this topic after the removal of the wreckage. Scientific publications on this topic will follow shortly.