Scientific Basis for Ice Regime System: Final Report

This report gives a summary of the work that was performed on behalf of Transport Canada to put the Arctic Ice Regime Shipping System on a more scientific basis. There are several aspects to the work. The report describes the seven Tasks for the scientific approach that were defined by the CHC. A summary of the results of the research into each Task is presented. In the final Task, the CHC made recommendations for a more scientifically-based system. These recommendations were discussed at a 1-day Workshop of all relevant AIRSS Stakeholders and were applied to a number of vessels to investigate the potential improvements. The recommendations have, as an underlying principle, that Operators with well-equipped ice-strengthened vessels with experienced Masters and accurate and timely ice information should be encouraged and rewarded. The data supports this view.NRC publication: Ye

Isolated ice floe impacts

This paper summarizes all available data related to ice floe impacts on structures. These data include laboratory tests, forces on several bridge piers (Hondo, Pembina, Rideau), forces from small icebergs impacting dedicated test structures (Grappling Island, Newmans Cove), first-year and multi-year ice impacts on the offshore structure Molikpaq, and the Hans Island experiments. The data represent ice masses covering ten orders of magnitude and impact forces covering seven orders of magnitude. The impacts were analyzed using various simple approaches and it was found that the impact force was best related to the kinetic energy of the floe at impact. This energy ranged over thirteen orders of magnitude in value. There was a good correlation of the impact force (F) with the energy (E) at impact with a function form F=A E0.532 where F is in MN and E is in GJ. The coefficient A was determined to be 61.7 for the "likely" impact force and 388 for the upper-limit impact force. The reason for this wide range is discussed and related to the wide range of ice strength and failure modes of the ice. The equation is applied to provide guidance on the forces for four different scenarios: (1) river ice impacts on bridge piers, (2) multi-year ice floe impacts on offshore drilling platforms, (3) isolated impact on the leg of a jack-up structure, and (4) impact forces on a Dynamically Positioned drillship with optimization of ice management. The analysis shows that as a rule-of-thumb, the likely impact force in kN is approximately the product of the square root of the mass (in kg) multiplied by the ice floe speed at impact (in m/s). \ua9 2011.Peer reviewed: YesNRC publication: Ye

The Significance of Ferroelectric Phase Transitions for the Earth and Planetary Interiors

With the compelling evidence for orthorhombic perovskite ABO3 structures in a major part of the earth's mantle, the question of whether any of these are ferroelectric (FE) or antiferroelectric should be of supreme importance. To answer this question the authors have conducted dielectric property studies at pressures up to 5.5 GPa on single crystals and polycrystalline aggregates of BaTiO3 as well as other FE materials representing FE polarization mechanisms. The results indicate that: (1) h.p.-induced FE phases are indeed likely to play an important part in the earth's mantle; and (2) existing FE state, occuring as elastic and dielectric inhomogeneities, can persist to much higher pressures than expected on the basis of the pressure dependence of isolated and unclamped FE crystals. It is suggested that the presence of FE states in the earth's mantle may be responsible for some of its anomalous elastic and dielectric features, especially its attenuating properties. It is conjectured that effects of FE states on properties of the Jovian planets might even be more prominant, especially those involving dielectric constant and polarization.NRC publication: N

Sliding resistance of grounded ice on clay in a laboratory: Potential implications for offshore design

10.1016/j.coldregions.2009.03.012Cold Regions Science and Technology581-21-14CRST

Properties of Decaying First-year Sea Ice at Five Sites in Parry Channel

This paper discusses three years of property measurements that were made on decaying first-year sea ice in the Canadian Arctic. Data were collected on five, level, landfast first-year ice sites in Parry Channel. Measurements, made from May to July/August, included the snow and ice thickness, ice temperature and salinity, and the in situ confined compressive strength of the ice (borehole strength). Ice properties at each of the sites changed dramatically as the ice decayed. Changes included gradual warming in the ice (until it reached an isothermal state), continual desalination of the ice and an 85 to 90 % reduction in strength compared to the winter maximum strength of first-year ice.NRC publication: Ye

The NRC Ice Load Catalogue

The National Research Council of Canada in Ottawa has developed an " Ice Load Catalogue ". This catalogue contains over 300 Events of ice loading on offshore and coastal structures. The catalogue contains information on the time-based behavior of the load as well as details of the ice conditions during each loading event. There is a complete range of structures that are included in the Catalogue including bridge piers, light piers, wharves, dams, offshore structures and natural islands. This paper presents an overview of the Catalogue. Each structure-type is described along with the instrumentation used to measure loads. A summary of available information is provided along with the load levels observed on the different types of structures.NRC publication: Ye

Evaluating the ISO arctic structures standard against full-scale empirical data

The ISO 19906 Arctic offshore structures standard presents a means for designing offshore platforms in ice-covered waters. This paper uses the Standard to predict loads for two simple scenarios. The predictions were made by an experienced ice engineer and an experienced engineer with no background in ice mechanics. Their predictions are compared to full-scale data. The comparison shows that different results can be obtained for the same scenario depending upon assumptions made (where there is little or no guidance in the Standard). The analysis highlights some of the factors that should be clarified in a revised version of the Standard. It is also suggested that sample calculations be included in a revised version. Overall, however, the users found the Standard helpful and relatively easy to use.NRC publication: Ye

Scoping Study: Ice Information Requirements for Marine Transportation of Natural Gas from the High Arctic

This report describes a scoping study that was performed to investigate methods for improving transportation in the High Arctic. Fourteen Captains of ice-class vessels were interviewed. They unanimously said that the detection and avoidance of multi-year ice was the key issue. They also indicated that better knowledge of regions where ice pressure and leads develop is important. A one-day Workshop was held with several key Stakeholders and issues related to improved systems were discussed. This report summarizes these findings as well as reviews the existing ice information systems, the Canadian Ice Service operations, and the use of ice information by the Canadian Coast Guard. A three-year program is suggested that would significantly improve detection of multi-year ice.NRC publication: Ye