Centrifuge modelling of ice scour in sand

Hynes, Frank (1996) Centrifuge modelling of ice scour in sand. Masters thesis, Memorial University of Newfoundland.

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Abstract

The interaction of icebergs (of glacial origin) and pressure ridge ice keels (formed from frozen sea water) with the seabed is recognized as an important consideration in the development of hydrocarbon resources in both the arctic and eastern offshore regions of Canada. To understand the detrimental effect of a scouring ice mass upon the integrity of seafloor facilities such as wellheads, pipelines and submarine cables, a large amount of analytical, experimental and phenomenological research into ice keel scour has been undertaken. -- Concerns related to the ice keel scour phenomenon are currently being addressed within a joint industry and government sponsored research program entitled the Pressure Ridge Ice Scour Experiment (PRISE). The objective of this program is to develop the expertise and understanding required for the safe and economical engineering of offshore pipelines in regions prone to ice keel scour. Under the auspices of the PRISE program, a series of centrifuge modelling tests involving ice keel scour were undertaken. The centrifuge modelling program involved towing an instrumented model ice keel of set geometry across a model testbed at a set scour depth while under the influence of a centrifugal force. The objective of the tests was to measure scour-induced stresses and pore pressures, horizontal and vertical loads and model keel/ soil interface pressures. -- The results obtained during the experimental program involving ice keel scour in sand highlighted the importance of the static soil "dead wedge" beneath the model ice keel with respect to variation in scour loads and subscour soil displacements. Analysis of the results served to support Been's (1990) shear dragging hypothesis. The results also suggest that a linear relationship can be used to describe the variation of scour loads with depth.

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