Pipeline route selection in an iceberg‐scoured seabed

Abstract

Abstract This paper deals with the geotechnical considerations in selecting a pipeline route through a seabed subjected to iceberg scouring. Most of the continental shelf of the east coast of Canada has been subjected to ice scouring. Some of the scours are relict, having occurred during periods of lower sea levels, but modern scours can be found from the Grand Banks north to the Arctic. Scours are sporadic on the Grand Banks, where they range in depth from about 1.5 m to 2 m, whereas in places off the coast of Labrador the entire seabed has been reworked by ice scouring and the depths of the scours are greater. Localized pits created by icebergs impacting the seabed are also found over most of the continental shelf area. These are typically less than 5 m deep, but they have been documented up to 10 m in depth. Models that predict ice scour depths have been published over the past several years. These models all assume that the ice is much stronger than the seabed soils. Recent evidence and analysis, however, indicate that ice keels may fail while scouring the seabed, with the result that existing models are not adequate and may tend to overpredict scour depth. This paper deals with the various interacting forces during the scouring process in sloping seabed conditions and includes discussions of the loads that are transmitted to the seabed and the considerations required for constructing and operating pipelines safely in ice‐scoured topography.