Impact Ice Pressure: More Questions than Answers

Abstract

Impact interaction between ice and engineering structures is always accompanied by ice failure. The failure modes can include crushing, cracking, bending, spalling, etc. Which mode is predominant depends mainly on the geometry of the colliding bodies, while the ice-induced impact loads depend both on the ice failure mode, and on the impact conditions. The earlier authors (Runeberg, 1888; Makarov, 1901) hypothesized that the ice-induced loads cannot exceed the strength of ice under corresponding types of loading. This presumption, which is now called the limiting ice strength approach, has been widely used as the basic criterion in specifying the design ice loads due to static (or quasi-static) and dynamic interactions. Here, the term “static” implies that the ice-structure interaction is not affected by the inertial forces of the interacting bodies. The “dynamic” or “impact” interaction has been thought of as the interaction which is either governed mainly by the inertial forces or when the latter may not be ignored. The wind-driven ice fields advancing on an offshore structure, a ship continuously progressing in consolidated ice, both can be treated as static or quasi-static interactions regardless of the advancement rate and the cyclicity of the induced load. A collision of a ship with an ice floe, or a wave-driven bergy bit hitting an offshore structure are the typical “impact” (dynamic) scenarios addressed in this work.