RIASSUNTO
ABSTRACT
Arctic business is developing within the sectors of marine operations related to offshore oil and gas, mining, seafood, tourism, scientific expeditions, and world trade shipping. As offshore activities in the Arctic is a relatively new field, with only a handful relevant operations to draw experience from, and since full-scale trials are extremely expensive, there is an expressed need for more detailed and cost-efficient analysis and design review of concepts based on numerical simulations. Over the years, various numerical simulators, with different levels of technical readiness, have been developed to address issues related to Arctic Offshore Engineering. This paper focuses on the development of the Simulator for Arctic Marine Structures (SAMS), its basic theories and recent engineering applications. These include structural damage assessment for simulating the impact between a wave driven glacial ice feature with a semi-submersible structure; the decision-making support by ice load calculations on a shipwreck in the Arctic; and various Arctic vessel navigation simulations. The technical advancement in terms of multi-body dynamics, ice fracture mechanics and hydrodynamics that the simulator is built on is manifested. The presented engineering applications signify the importance, the versatility and maturity of SAMS in dealing with complex ice – structure interaction issues at different scales and at various levels of complexities.
INTRODUCTION
For Arctic structural design and most Arctic operation planning, ice load calculations are one of the key components. However, ice load calculation is complicated by various ice conditions and different ice failure modes. As Palmer et al. (1983) stated, ‘it is no more likely that there should be a universal ice-force formula than that there should be a universal formula for the force on a body in a moving fluid, and in the present state of knowledge, it would be unwise to expect too much’. Over the years, the common engineering practice, e.g., (ISO19906, 2019), in calculating ice load on a given structure takes several steps of presumptions: an assumption on the limiting mechanism and an assumption on the various possible failure modes (Løset et al., 2006, Sanderson, 1988, Palmer and Croasdale, 2013). These approaches often offer one design value and are handy for fast calculations, however, require high engineering experience in making sound judgements. As time steps into the new century, our computational power and tools are getting more advanced. In addition, our understanding towards the mechanics of ice – structure interactions are also ever growing thanks to more accumulated data and theoretical advancement. It is now at our disposal to 1) get rid of all those initially needed interaction scenario presumptions and start from the beginning with given ice condition and structure 2) to obtain time domain analysis of both the ice action and its effect on the structure; 3) in addition, these calculations can be so fast that an almost real-time domain analysis becomes possible, which opens door for simulations of Arctic marine operation. Given the background and targets, the Simulator for Arctic Marine Structures (SAMS) is developed over the past 8 years. This paper documents the theoretical background of SAMS and its recent applications.