Abstract
Ice action on ships and offshore structures is commonly determined by calculating the contact ice pressure. The aim of this paper is to describe the empirical background for determining the ice pressure. This review article describes six different test series where ice edge indentation and contact ice pressure have been investigated. These test series are ice pressure measurements onboard IB Sisu in the Baltic in 1977, pendulum tests carried out at Arctec in Ottawa, Canada, in 1979, laboratory and full scale ice crushing tests at WARC in 1988 and onboard IB Sampo 1989, medium scale indentation tests on Hobson's Choice Ice Island 1990, ice crushing tests at NRC, Ottawa 1992 and the JOIA tests in Hokkaido 1996–1999. These tests were selected as at each series a new phenomenon was observed. The aim of the paper is to introduce the main features for ice–structure contact empirically through the description of tests. The paper is concluded with a short description of the existing models for ice pressure, especially to gain an insight and highlight the main observations in each test series and how the models for ice pressure have developed based on the observations.This article is part of the theme issue ‘Modelling of sea-ice phenomena’.
Highlights
When a ship collides with an ice edge or ice cover drifts against a stationary structure, the force acting between the structure and ice is transmitted through the contact between the structure and ice
Why ‘ice edge’? When a level ice sheet drifts against a stationary structure that offers a vertical side against the ice, the meaning of ice edge and its geometry is clear
— the measured ice pressure is clearly higher than the uniaxial compressive strength of ice, up to 8.5 MPa;
Summary
When a ship collides with an ice edge or ice cover drifts against a stationary structure, the force acting between the structure and ice is transmitted through the contact between the structure and ice. As the contact (loosely) includes an area where the contact exists, instead of the contact force, the contact is described by contact pressure, 2018 The Authors. ‘local’ refers to ice deformation and a failure occurring at the contact. One immediate note in this description is that ice is always considered to break—in most cases ice is forced to fail to let the ship progress further or the ice cover drift to continue. The present description of ice edge failure and ice pressure reviews a set of experiments carried out to observe the contact between an indenter (in full scale structure/ship) and ice edge, and to measure the ice pressure. The quality of these leaves a bit to be desired
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