In-plane fracture of an ice floe: A theoretical study on the splitting failure mode

•The splitting failure of an ice floe is studied.•LEFM and Cohesive Zone method are combined with the weight function method.•Plastic limit theory has been employed to analytically calculate the ice splitting load.•The influence of ice floe size, lateral confinement and inertial effect are studied.

In practical offshore structure/icebreaker designs, it is critical to capture the salient failure modes of the ice feature. The dominant failure modes are influenced by the structural properties, interaction process, and characteristics of the ice features. For an ice feature of finite size with relatively small lateral confinement, splitting failure has been frequently observed during ice-structure interactions. In literature, the splitting failure of an ice floe has been studied using several different methods, ranging from strength theory to methods based on fracture mechanics. One contribution of this paper is that these various methods are compiled and evaluated collectively. Another contribution of this paper is the construction of an analytical framework to obtain solutions for the splitting process of an ice floe upon serious considerations of relevant fundamental theories. The framework developed for its calculations is presented but not limited these two base cases (i.e., rectangular and circular ice floes). Specifically, because of the complexity of the splitting failure scenario (particularly the ice floe geometry) and our pursuit of analytical solutions, within the presented framework, two different approaches have been proposed: the fracture mechanics approach and plasticity theory approach. All of the employed methods are validated against data from previous field tests or numerical results. Recommendations and discussion were presented for each of these methods' respective application range. It was found that most of the floe sizes under engineering interests can be accurately described by linear elastic fracture mechanics. The cohesive zone method, which is one type of the nonlinear fracture mechanics based approaches, is found to be potentially applicable in extrapolating laboratory-scale measurements to the field scale. Worth mentioning, the weight function method was effectively used to calculate the fracture properties of an ice floe under various symmetric loading conditions (e.g., boundary confinement). The boundary confinement can easily prevent splitting failure or increase the ice splitting load. As one type of the lateral confinement, the inertia-induced body force, is also studied and compared with previous numerical results. Comparatively, the plasticity theory based approach (i.e., the plastic upper/lower limit theory) enables us to effectively attain a conservative estimation of the ice splitting load in an analytical form. It can serve as a supplementary tool to the fracture mechanics based approach.