The design of buried offshore pipelines in ice environments must consider extreme load events. Current practice for the characterization of geotechnical loads (i.e. system demand) and pipeline mechanical resistance (i.e. system capacity) has limitations due to idealizations and uncertainties associated with statistics of physical data sets, experimental techniques and engineering models used in analysis and design. Advancements in computational methods have provided improved engineering tools to analyse complex nonlinear geotechnical failure processes, load transfer and pipeline/soil interaction events and pipeline failure mechanisms. Probabilistic methods provide an objective, rational and quantitative framework to optimize design options with respect to technical, economic and environmental criteria that meet specified target safety levels.

INTRODUCTION

Based on current energy demand, there exists significant potential for the development of offshore hydrocarbon basins located in arctic and ice covered waters of the northern hemisphere. Some of these regions with active operations or proposed field developments are presented in Fig. 1. The exploration and development of oil and gas reservoirs in these environments present technical and logistical challenges for the engineering design, construction and operation of surface infrastructure and subsea facilities. These challenges may impact project viability, execution or cost. Load events such as ice gouging and strudel scour, due to natural environmental processes, and thaw settlement and frost heave, due to operational and geotechnical factors, can impose large ground deformations on buried offshore pipelines. These geohazards have the potential to affect pipeline operations and may result in a loss of pressure containment integrity. A pipeline section may warp or ovalise affecting serviceability limit states, or more severe deformation mechanisms may occur that exceed ultimate limit state such as local buckling or through wall rupture. These issues directly impact economics and may have environmental consequences. From this perspective, engineering models are developed to assess strain demand (i.e. loads), load effects (e.g. pipeline/soil interaction) and strain capacity (i.e. pipeline mechanical response limits).

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