Abstract

This paper discusses mathematical models of iceberg towing that considered iceberg shape characteristics in an explicit form. These models allowed to analyze oscillations appearing in towing system at begging of iceberg motion and during its mode change, when dynamic action is applied into stationary towing process. The obtained results showed good consistency and wide possibilities for investigation of non-linear processes appearing in the single line iceberg towing systems. Evaluation of the forces peak values allowed to formulate recommendations for safe and efficient iceberg towing operations.

Introduction

For safe prospecting and exploration of the Arctic shelf a complex ice management system is required. Physical impact on drifting icebergs is one of the means to prevent their collision with offshore drilling rigs. The most effective way of changing iceberg's drift trajectory is its deflection with the help of a tug vessel equipped with special towing system. This operation is complicated by a number of technological challenges associated with the iceberg and towing system interaction, their dynamics, etc. Some of the recently published works are devoted to theoretical study of the iceberg towing process works (Eik et al., 2010; Yulmetov et al, 2016; Yulmetov et al., 2017; Marchenko et al., 2005).

In (Marchenko, 2010; Sazonov, 2010) the issues of the towing process stability have been analytically investigated, as well as a numerical study of the oscillations appearing in the "vessel-rope-iceberg" system. At the same time, authors underline the need to reduce the vessel acceleration time at the beginning stage of towing due to maneuverability problems experienced by the vessels at low speeds. At present, problems of dynamical processes taking place in the towing system and significantly effecting safety and reliability of the icebergs towing process remain to be the least investigated. The above mentioned publications include very rough approximations of the icebergs' shape, that significantly effects dynamics of their behavior in towing process and, hence, the appearing oscillations.

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