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Title: Experimental study of ice gouging in a sand seabed
Author: Giuliani, Giorgio
ISNI:       0000 0004 2745 8644
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2013
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This thesis aims to investigate ice gouging processes in general and the influence of geotechnical parameters on subgouge deformation. A sand channel has been built up at the University of Aberdeen where a number of scaled models of iceberg have been tested. A number of scaled models were manufactured with a base 150 x150mm and different shapes (specifically with the front face angle of 90°, 75º, 60° and 30°) to represent the part of the iceberg below the water line as a rigid body. During the tests several parameters were varied such as: the velocity at which the iceberg models were towed/moved, their mass and shape, and the soil density. All tests were performed in cohesionless soil, dry silica sand placed in a wooden channel. At this stage two different types of tests were carried out: tests at free penetration and tests at fixed penetration. The effects of the iceberg geometry under these various conditions were explored using an instrumented model gouge, with particular attention paid to the resulting tow force and penetration. Tests at free penetration showed that the penetration (P) of the object into the seabed is influenced by its weight and shape as it increased with an increase of the mass and the front face angle (P90º > P75º > P60º > P30º). The drag force (F) is also considered and it increases with an increase in penetration and mass of the object due to the mound of sand formed at front. For tests at fixed penetration (20mm and 30mm depth from the top surface) the attention was on the drag force which was influenced by the shape of the ice models (F90º < F60º < F30º). Pressure sensors were positioned inside the tank from the start point aligned long the same vertical. The purpose was to measure the stress within the seabed during the ice gouging event exerted by the front mound formed on the front of the object. Results showed that the pressure induced by the object decreased with the depth. The test results were compared to an empirical model developed by Kioka (2006) and Barrette (2011). A burial depth of pipeline has been proposed based on the physical gouge model which may allow trenching contractors to make better predictions of ice gouging performance in sands.
Supervisor: Not available Sponsor: National Subsea Research Institute
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available