Figure 19 gives appropriate locations for measuring the depth at the structure, ds.
Strength
Shore protection structures must be strong, and this can only be achieved by using either massive
and heavy components that cannot be dislodged by waves, or smaller components that interlock to form a
large mass. The problem with small interlocking units, such as concrete blocks, is that they exhibit little
reserve strength. That is, once damages occur, they generally progress to complete failure.
Flexibility
Flexibility is also desired because it allows structures to compensate for settlement, consolidation
and toe scour. The revetment shown on Figure 20 illustrates this point. The massive individual concrete
slabs could not be moved by waves, but the structure failed because it was not able to adjust to erosion
that occurred around the ends and through cracks between the slabs.
Toe Protection
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