Flexural failure of ice on conical structures can produce a rubble pile or pile-up on the face of the cone. These features can increase the load significantly and affect the failure mechanism of the ice. Behaviour of rubble piles has been the subject of several ice tank programmes as well as limited programmes in the field. Using the data from the Confederation Bridge Monitoring Programme, observations pertaining to the rubble pile will be presented. The available video data allows for a continuous observation of rubble pile formation and behaviour and determination of the characteristics of the rubble pile. These characteristics include the size, shape, parent ice thickness, and piece size in the rubble pile, the effects of velocity, friction with the ice cover, and friction on the cone. The observations will be compared to existing theories on rubble pile formation and behaviour.
Flexural failure of an ice sheet that interacts with a conical structure is one of several possible ice failure modes observed on offshore conical structures. Measurements and observations have shown that the highest loads occur when a significant rubble pile is present. Given the importance of the rubble pile, there have been several attempts to describe the behaviour of an ice rubble pile, some even with limited field observations. The Confederation Bridge Monitoring Programme (Brown et al. 1999) provides real-time data for ice interactions with the structure. The data from this programme is subject to a five-year confidentiality agreement that prevents publication of any specifics relating to the ice events. Using the data from the Confederation Bridge Monitoring Programme, a series of observations, both quantitative and qualitative, of sheet ice rubble piles have been made. The two primary quantitative observations relate the ice thickness and ice sheet velocity to the rubble pile height.
