Numerical experiments on ice-structure interaction in shallow water

Abstract

This paper studies the ice-structure interaction process on a wide, inclined, offshore structure in shallow water. In such a process, the ice rubble pile that forms in front of the structure may reach the seabed, or in other words, the rubble pile may ground. A grounded rubble pile is often assumed to protect the structure from high peak ice loads. The study is based on two-dimensional combined finite-discrete element method simulations and it focuses on the effect of water depth and ice thickness on peak ice load magnitudes. In order to obtain a better understanding of the physical phenomena behind the peak ice load events in shallow water, we analyse the probability of rubble pile grounding, the rubble pile geometries, and the load transmission from the intact ice sheet to the structure through the ice rubble pile. We also discuss the parameter effects and the probability and severity of ice encroachment in shallow and deep water. Our simulations suggest that an interaction process in shallow water may lead to higher peak ice load magnitudes than an interaction process in deep water. This is at least the case when there is no pre-existing, partially consolidated ice rubble pile in front of the structure. We also observed that the ice thickness influences the probability of rubble pile grounding: For a given ice thickness to water depth ratio, thin ice appears to ground with higher probability than thick ice.