This paper presents an approach to rock cover design for un-trenched pipelines installed on the seabed and rock-dumped for protection against dropped objects, anchor chain impact and fishing/trawling activities. This is found in some North Sea locations which present challenging conditions for trenching while protection is necessary due to intensive fishing activities.
Under these circumstances the pipeline must remain within the rock berm and, hence, it must be designed against global buckling. Whereas there are clear design guidelines addressing upheaval buckling behaviour, the resistance to lateral buckling to maintain a pipeline within the rock berm has received less attention in the literature.
The aim of this paper is to present a method to design a rock berm to mitigate against lateral buckling of rock-dumped pipelines based on the horizontal out-of-straightness survey data provided to the designer. The main challenges associated with this activity at different design phases are also introduced, including the use of analytical tools as well as detailed finite element analysis.