Abstract
[Truncated abstract] Offshore pipelines form an integral part of any offshore hydrocarbon production field and ensuring the security of these vital 'arteries' from either environmental or operational hazards are of paramount importance. This thesis is concerned with the changing strength of soft seabed sediments through the processes of consolidation and disturbance, as these sediments form and interact with seabed infrastructure. These processes involve failure and remoulding, as well as healing through reconsolidation. Therefore, it is necessary to consider alternating episodes of cyclic loading and recovery in cases involving storms and the intervening calm periods, pipeline startup and shutdown episodes, and the triggering, runout and reconsolidation of mass movement events – including their impact and flow past pipelines. An important theme is the whole life response of a sediment during genesis and when acted on by seabed infrastructure. Rate effects are particularly important considering the wide range of strain rates involved in these processes – from slow changes during consolidation, to the rapid strain rates within submarine slides. The effect of clay microfabric arrangement during monotonic and subsequent cyclic strength degradation is explored using centrifuge cyclic T-bar tests.
Original language | English |
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Qualification | Doctor of Philosophy |
Publication status | Unpublished - 2013 |