Predictions of ice scour loads from small scale tests under 1 g conditions

Rate effects during ice scour in sand

“…The wall friction angle δ between the fontal face of the iceberg model (line OA in Figure 9) and the soil cannot be considered to be fully mobilised and its value will remain between +δmax< δ< -δmax. As discussed by Arnau and Ivanovic (2015), the wall friction angle δ was determined experimentally for a range of rake angles with good correlation with the theoretical values proposed by Hettiaratchi and Reece (1975). For the analysis presented herein, the soil-soil interface angle (line A'B' in Figure 9) will be assumed to be λ = φcrit as suggested by Hettiaratchi and Reece (1975).…”

“…All these models treat the ice scouring process as a drained event, even though the mean drifting speed of several icebergs around Grand Banks was found to be 0.22 m/s (Smith and Donaldson, 1987) which in combination with a low permeability seabed can develop undrained or party-undrained scouring conditions. The same methodology described by Hettiaratchi and Reece (1975) was used in the present study to calculate the scour loads in dry sand (Fstatic) and a detailed explanation of how to compute Fstatic for a range of iceberg geometries and soil properties can be found in Arnau and Ivanovic (2015) and Arnau (2017). Figure 2 shows the geometry of the soil failure mechanism created in front of an iceberg model with the frontal face inclined at an angle α = 150˚, for example.…”

“…4, the following adjustments shown in Eq 7 and 8 were required, where δ (Table 3) can adopt positive and negative values (e.g. +δmax< δ < -δmax) as discussed in Arnau and Ivanovic (2015).…”

“…A number of physical modelling studies have been undertaken to investigate the ice scour process either through small scale (e.g. Arnau and Ivanovic, 2015;Kioka et al, 2000;Abdelnour and Graham, 1984;Barker and Timco, 2002), large scale (e.g. Peek et al, 2013;Liferov and Høyland, 2004) or centrifuge tests (e.g.…”

Improving seabed cable plough performance for offshore renewable energy

“…To provide protection from offshore hazards such as seabed trawling (Ivanovic et al, 2011), anchor damage and iceberg scour (Arnau and Ivanovic, 2015), offshore subsea power cables are required to be buried to depths of up to 3 metres. Seabed ploughing has been used extensively in the oil and gas industry to provide protection for subsea pipelines with diameters of up to 1.5 metres, and this has been the main focus of research to date (Lauder et al, 2012, Lauder et al, 2013.…”