Abstract:
This document reviews the scour protection systems required around port structures
where these are to be used for the berthing of vessels powered by water jet systems.
The development of a scour protection system at Poole Harbour in Dorset has been
documented and reviewed and a series of laboratory investigations were then
undertaken. This has enabled a greater understanding of the scour mechanisms from
the water jet propulsion systems of High Speed Ships. This work has shown that
current design guidance on scour protection is not appropriate for use on berths used
by High Speed Ships, that failure of these systems can occur rapidly and
catastrophically, and secondary effects from water jets may promote the failure of
quay walls. The scour protection system should comprise two individual elements, a
filter layer and an armour layer. It has been found that systems involving individual
isolated armour units are inappropriate and prone to failure and that shaped linked
armour blocks need to be used. The loads on the armour layer were also found to be
oscillatory and the materials used for both the armour and filter layers need to be
designed for cyclic fatigue loading and fretting. Water jets are also capable of
reducing the strength of permeable, seabed strata.
