Objectives of the project

Coastal structures in northern and central European waters as well as offshore structures for exploration and production of hydrocarbons from the European Arctic have to be designed to withstand the forces caused by moving ice. These ice forces govern the design in most cases where ice is present. The largest ice forces are caused by pressure ridges and by level and rafted ice on vertical structures.

About these ice forces there exist an extraordinary uncertainty between the predictions of scientists around the world. Such predictions scatter for identical conditions by a factor of 10 to 15. Recent findings from several full scale measurements indicate that ice forces on vertical structures are indeed 10 times smaller than they have been used for their design. This could mean, that coastal structures and bridge piers are significantly over-designed.

The overall objective of the project is to prove the validity of lower ice forces, and to have the results accepted by authorities and users, and ultimately incorporated into an EUROCODE. This will be only successful if the research is technically and scientifically of highest standard without leaving any doubts in the results.

Methods applied

In order to achieve this goal, the following research program is executed:

• The central part of the project are full scale measurements of forces caused by level ice and ridges using an existing device and field laboratory - the Lighthouse Norstrømsgrund located in the northern part of the Gulf of Bothnia in the Northern Baltic Sea. Ice forces are measured by mounted load cells at different pressure areas. This includes accurate and complete characterisation of ice features (level ice and ridges) interacting with the lighthouse by means of ice sampling and subsequent laboratory tests as well as optical / video monitoring. In this conjunction the fracture toughness of level ice, the strength of consolidated and unconsolidated parts of ridges and the documentation of the ice failure process are obtained.

• Developing ice load spectra from various ice conditions as input information for probability predictions and study ice - structure contact and ice failure processes in order to establish the theoretical prediction models on the basis of realistic failure conditions.

• Intensive and analysis of newly acquired data as well as consistent merging and combined / comparative evaluation of the new data with historic ones and especially those acquired during the LOLEIF project.

Innovation

The achievements of the STRICE project are expected to result in

• a fundamental insight into the problem of ice structure interaction based on full scale measurements of real ice and not on model tests with model ice,
• comprehensive and extended data sets of ice load measurements conducted on full scale under real natural conditions,
• improved ice force prediction models and probability statistics based on most extensive field and laboratory studies,
• the elucidation of the controversy on ice forces,
• validation of low ice force levels for the case of ice breaking against vertical structures.

The results will

• provide governmental authorities and classification societies with substantial information on ice forces on coastal, offshore and structures on inland waters (estuaries, rivers, lakes),
• provide the basis for the development of an EUROCODE for ice forces,
• drastically reduce the costs for structures to withstand ice loads in future designs,
• open new possibilities for technical and scientific developments.

These activities will yield recommendations of ice forces on vertical structures from level ice and ridges which will be elaborated in consultation with the classification societies and will support the development of an EUROCODE for design of structures in ice.

The STRICE project combines the efforts of experts of eight research partners from six European countries (Finland, France, Germany, Norway, Sweden and the United Kingdom) working together for three years with substantial resources in collaboration with specialists from Canada, Japan, Russia and the USA.