The disturbance of the seabed that comes from natural processes, like iceberg keels, presents a potential issue for the installation of pipelines. The zone of soil disturbed by the iceberg and the soil resistance force to the object movement is of interest to the offshore geotechnical engineer. This paper reports experimental investigation of an iceberg keel shape penetrating sediment and discusses the influence of the depth of penetration on the drag force with its corresponding components. The study was aimed at estimating the drag force and its components in relation to scour developed and the shape of the iceberg. It involved laboratory experiments in which the effects of scaled iceberg models of different shapes were examined. These models were tested in sand channel. The results indicate an increase in penetration and drag with increasing front face angle for the free penetration case, but an opposite trend for the fixed penetration case.
Determining the burial depth of a pipeline at which it remains safe from any contact with an iceberg has been of concern in recent years. A number of experimental and numerical studies have been undertaken to address this issue. During the movement of an iceberg, the soil below the scouring ice keel will displace laterally, in the direction of ice keel movement, transverse to the ice movement and vertically (as reported by Palmer et al., 1990; Woodworth-Lynas et al., 1996). The seabed affected by an ice scour process is described generally in terms of three zones (Palmer et al., 1990). Zone 2 is situated below the level of the base of the ice keel and is subjected to large plastic soil deformations. Zone 3 is where the soil deformation is limited to elastic behaviour and is usually deemed as a safe zone.