The performance of pipeline ploughs traversing seabed slopes

TY - JOUR

T1 - The performance of pipeline ploughs traversing seabed slopes

AU - Bransby, Mark

AU - Barlow, David T

AU - Brown, Michael

AU - Davidson, John

AU - Brankin, Stuart

AU - Robinson, Scott

N1 - no funding info

PY - 2018/1/15

Y1 - 2018/1/15

N2 - Ploughing is a method used to bury pipelines beneath the seabed. In this method, a large purpose built plough is pulled by a support vessel to create a trench into which a pipeline is lowered. The soil that has been removed is then placed or back filled over the pipeline to provide thermal insulation, protective cover and to prevent upheaval buckling (UHB) due to pipeline thermal expansion. The majority of previous research effort has focussed on the behaviour of ploughs on level seabeds and has not investigated common geohazards such as sloping seabeds. There is also limited guidance available to industry on the limitations of ploughing on slopes. This paper reports a series of experimental tests conducted to investigate how ploughs may behave when seabed slopes are encountered and ploughing has to traverse cross-slope. The results show that ploughing operations can still be undertaken when traversing a slope but that the efficiency of operations is reduced with increasing slope inclination, leading to a reduction of trench depth and spoil heap sizes on steeper slopes. This may result in reduced pipeline cover depths on slopes if these effects cannot be mitigated.

AB - Ploughing is a method used to bury pipelines beneath the seabed. In this method, a large purpose built plough is pulled by a support vessel to create a trench into which a pipeline is lowered. The soil that has been removed is then placed or back filled over the pipeline to provide thermal insulation, protective cover and to prevent upheaval buckling (UHB) due to pipeline thermal expansion. The majority of previous research effort has focussed on the behaviour of ploughs on level seabeds and has not investigated common geohazards such as sloping seabeds. There is also limited guidance available to industry on the limitations of ploughing on slopes. This paper reports a series of experimental tests conducted to investigate how ploughs may behave when seabed slopes are encountered and ploughing has to traverse cross-slope. The results show that ploughing operations can still be undertaken when traversing a slope but that the efficiency of operations is reduced with increasing slope inclination, leading to a reduction of trench depth and spoil heap sizes on steeper slopes. This may result in reduced pipeline cover depths on slopes if these effects cannot be mitigated.

KW - Offshore pipeline ploughing

KW - Physical modelling

KW - Sand

KW - Slopes

UR - https://www.scopus.com/pages/publications/85034220234

U2 - 10.1016/j.oceaneng.2017.11.028

DO - 10.1016/j.oceaneng.2017.11.028

M3 - Article

SN - 0029-8018

VL - 148

SP - 125

EP - 135

JO - Ocean Engineering

JF - Ocean Engineering

ER -