A dynamic model for breaking pattern of level ice by conical structures

摘要

This thesis focuses on the simulation of conical structure breaking level ice. The simulation uses a new framework for ice-load models. The framework is based on observed ice failure events at full scale and at model scale (ice tanks). The conceptual model simplifies the ice failure process as a nested hierarchy of discrete events, including the three continuum processes of crushing, bending, and rubble formation. The study of this thesis specifically focuses on the first two processes mentioned above - namely crushing and bending. The aim of the study is to develop a model for establishing the time history of ice load during the interaction of level ice with a conical structure. A fixed mechanical ice failure model of contact-crushing-bending was employed in the study. An ice thickness-velocity dependent radius of ice floe is assumed. The interaction was simulated computationally by geometric grid method (GM) based on the mechanical ice failure model. The breaking pattern of the ice sheet is determined and a force time history is obtained based on an assumed failure load and GM. A comparison is made between the analytical method and GM. The comparison results show that the GM is reliable. A breaking process is investigated with GM with a specific ice edge using the jacket platform of JZ20-2MUQ, and a computational result was obtained. The results showed a vibratory response. The result of the study was applied to model the response of an offshore structure, JZ20-2MUQ. A comparison between the computational experiment and full-scale measurement was made. The comparison of the full-scale measurement and the calculation match well.