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is not normally at positions of highest bending moment
or stress. As a consequence, holes in sheet piles do
not present a risk of catastrophic collapse until the
attack is advanced. The structure will often successfully
bridge damage. This is possible because ALWC attack
is not uniform, unlike normal marine corrosion, steel
adjacent (within 100mm) to a hole may be virtually full
thickness.
However the loss of backfill through holes will have
structural effects. The subsidence under paving may
go undetected. Paving hanging up on quay capping or
piles may not immediately fall into the void.
Illustrated here is a depression in the paving ‘developed’
by the recent rain, this masked a void which was filled
with 100 cu metres of concrete the following day (See
image 1). An important safety alarm must therefore
be sounded. Forklifts have fallen into such voids. People
are at risk.
Revetments may collapse and flood defences may be undermined
and breached, while sheet piling remains standing.
See:
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