(Figure 11). The 8-tonne Core-Loc armor layer was rebuilt resulting in a pack-
ing density of 0.60. The buttress material was displaced between Profiles 4 and
5 and between Profile 8 and the elbow of the structure during 13-sec, 3-m waves.
Core-Locs in the vicinity of Profile 4 began to slide seaward, but the structure
remained stable. However, the buttress was removed during 13-sec, 3.7-m
waves between Profiles 4 and 6 and toe units in this region began to move.
Eight-tonne units were displaced between Profiles 4 and 5 during 16-sec, 3.7-m
waves and a hole developed at the crest near Profile 4 (Photo A10). The larger
units, 11 tonnes, remained stable during Plan 1A tests (Photos A11 and A12). It
was noted that the steep approach slope and the shallow depth in this region pro-
duced breaking waves that plunged along the toe region. The plunging breakers
caused apron material to erode and forced the toe Core-Locs away from the
structure.
Plan 1B
Plan 1B was identical to Plan 1 except three widths of bundled steel chain
were placed along the toe from Profile 4 to the elbow (Figure 12). A single
chain was placed at the toe at the elbow to the terminus of the quay wall. Addi-
tionally, a single chain was placed around the toe of the tetrapod section. The
purpose of the chain was to stabilize the toe to observe the stability of upslope
units. Rebuilding of the 8-tonne Core-Loc section resulted in = 0.60. The
addition of the chain stabilized the Core-Locs at the toe; however, wave energy
also displaced the chain and it was necessary to reposition the chain between
wave series. The armor layer loosened between Profiles 4 and 5, and apron
material was displaced for wave conditions up to 17-sec, 5.2-m, but the section
remained stable (Photo A13). During the 17-sec, 5.2-m condition, 11-tonne units
at the toe near Profile 10, which was unprotected by the chain, were removed by
waves, causing the upper units in this area to be displaced. A hole developed in
the armor layer near the crown at Profile 10, which increased in size and
migrated "north" along the structure (Photos A14 through A16). Additionally,
green water overtopping was observed over the +5-m CD breakwater section for
waves 3.7 m in height and greater. The severe breaking condition migrated to
deeper water as peak period and/or wave height increased.
Plan 1C
Plan 1C was the same as Plan 1B except three widths of steel chain were in-
cluded along the toe from Profile 4 to the leeward side of Profile 11 for Plan 1C
(Figure 12). In addition, the chain was anchored to the breakwater at approx-
imately 8-m (prototype) intervals using pins inserted under the structure. The
breakwater was rebuilt prior to experiments and the resulting packing densities
for the 8- and 11-tonne Core-Locs were 0.62 and 0.59, respectively. The struc-
ture was stable for waves up to 6.7 m, but it was observed that the armor layer
loosened in areas between chain anchors. During 16-sec, 6.7-m waves, one
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Chapter 3 Results
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