Modelling the Dynamics of Iceberg-Soil Interaction during Seabed Gouging

Not only in the Arctic, but also well outside the Arctic, icebergs can be a danger to buried offshore pipelines due to seabed gouging. As it is not economically feasible to bury these pipelines at depths where soil deformations are small, these pipelines are buried at sub-gouge depths where the soil experiences significant plastic deformations. Before considering the sub-gouge soil deformations that are vital to determine optimal pipeline burial depths, a better understanding of dynamic iceberg-soil interaction during seabed gouging is required. In the past, several models have been developed to describe the interaction forces between an iceberg and the soil in front of the iceberg keel based on static soil failure theory or from experimental observations. These models do not fully account for the dynamic behaviour of the iceberg, nor do they consider the corresponding response of the sub-gouge soil. In fact, how the extent of sub-gouge deformations depends on the geotechnical parameters of the seabed is not at all well understood. Therefore, a three-dimensional physics-based model is being developed that describes the transient iceberg-soil interaction (i) based on plasticity theory, (ii) accounting for the dynamic response of the iceberg during gouging and (iii) including the hydrodynamics of the iceberg. This paper presents a two-dimensional version of the iceberg-soil interaction model assuming the iceberg keel to be rigid and plane-strain conditions for the soil. Model predictions are presented and compared for different seabed characteristics.