Failure mechanism of cutting submerged frozen clay in an arctic trenching process

Abstract

This version of the thesis only covers the literature study. The results analysis and conclusion of the thesis are confidential. Pipelines in arctic waters are at risk of being damaged by gouging ice masses. To protect these pipelines, they can be buried in trenches. When trenching in arctic clayey soil, sub sea permafrost can be encountered. The main objective of this research is to study the failure mechanism of frozen clay as encountered in permafrost regions. Knowledge of the cutting mechanism leads to the ability to calculate cutting forces and the specific energy required to excavate material. To find the failure mechanism and answer the research question, a cutting setup was designed and built and cutting experiments were conducted. The setup was designed, based on requirements that result from studied literature on frozen clay and cutting theories. A series of cutting experiments were conducted where a slab of frozen clay was pressed against a transparent wall and the top layer was cut off while filming the process with a high speed camera. The results are measurements of the cutting forces and observations of the failure mechanism.