A 3-DIMENSIONAL EULERIAN FINITE ELEMENT MODEL FOR ICE SCOUR

摘要

The main objective of this paper is to present a Finite Element (FE) numerical model of the ice scour process. The FE model is developed to study the soil deformation and transport process around the scouring ice and to investigate the effects of the ice scour on a pipeline buried or laid in a trench cut on the seabed. The focus of this paper is on the scours caused by ice ridges commonly observed in the Beaufort Sea. The developed FE model is a new application of the Arbitrary-Lagrangian-Eulerian (ALE) method to a soil mechanics problem involving very large deformations. Soil material, originally positioned in front of the ice ridge, is transported forward and sideways through the FE mesh and deposited in the berms formed on both sides of the scour. The soil material below the scour depth similarly moves across the mesh simulating the subscour effect. An inviscid CAP plasticity constitutive model is used to model the soil material. This paper focuses on the interaction between the ice ridge and the seabed. It describes soil transport process involved during the interaction. The soil deformation field obtained from the model is compared with the empirical deformation functions commonly used in current design methods. Future papers will report on the interaction between the ice ridge, the infill in the pipeline trench, and the pipeline; the influence of the soil properties of the trench and the seabed will also be studied.