Analysis for splitting of ice floes during summer impact

Abstract

Impact loads during the summer from large, storm-driven, multiyear ice floes are an important consideration for offshore structures in the Beaufort Sea. It is possible that an impacting multiyear floe will split into two or more large pieces which rotate around the structure. This paper presents a fracture-mechanics based analysis of this phenomenon. The phenomenon of floe splitting is a consequence of initiation and propagation of radial cracks in the impacting floe. The crack propagation problem is studied here by means of methods of linear elastic fracture mechanics. Required crack tip stress intensity factors are evaluated numerically using a finite element method. It is shown that the splitting load or the fracture limit load will be reached relatively early in the radial crack propagation process, such as when the crack length is a small fraction of the floe size. Subsequently, the crack can propagate dynamically, splitting the floe into pieces and consequently, the load on the structure will fall.