Burial of submarine pipelines, umbilicals and cables has proven to be an efficient measure for protection against trawling and anchoring. Since the 1980s, extensive burying of both existing and new submarine cables has lead to a considerably decrease in the number of failures and accidents. While in the available standards and recommended practice, no particular guidance can be found related to a safe burial depth in different soils, a number of studies have been carried out showing that a burial depth of 0.6m provides good protection against trawling and fishing activities in most soils. In the meantime, a demand has developed for even deeper burial depth, especially in soft soil in order to protect also against light fishing anchors.A review of the available literature has been carried out in order to determine the possible range of penetration of trawl board in different soils and under different conditions. This showed that the penetration remained limited whatever type of trawl gear or type of soil.In addition, calculations have been performed in order to assess the penetration of trawl boards with different sizes, weights and a range of soil strength. The results show a good agreement with the observed data, confirming that the penetration of trawl gear will be very limited in most clays with exception of very soft clay where excessive penetration can be expected.To assess anchor penetration, a software predicting the behaviour of drag embedment anchors during penetration in clay has been used. The maximum expectable penetration for different anchor sizes and soil profiles has been calculated and are presented in this paper. The results from these calculations also show that for most of the soils, the penetration of an anchor from a light fishing boat will be limited.
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