11-tonne and three 8-tonne toe units were displaced. The toe failed near Profile
10 during 19-sec, 6.7-m waves at a location where the chain was forced seaward
between anchors (Photos A17 through A19).
Plan 1C was rebuilt and repeated with additional pins used to anchor the
chain to the structure. Packing densities remained the same as the original
Plan 1C. The plan was subjected to the entire storm series and was moderately
stable. Three 8-tonne units were displaced between Profiles 4 and 5, and two
11-tonne units were displaced between Profiles 9 and 10 (Photos A20 through
A22). All displaced units originated at the toe.
Plan 2
Based on observations of the model and conversations with JV RRI-BCEOM
personnel Messrs. A. Merrien and L. Fischer, Plan 2 consisted of raising the
+5-m head portion of the breakwater to bring the entire structure to +8 m to
reduce overtopping. The 8-tonne units were replaced with 11-tonne Core-Locs
and the toe was reinforced with additional 11-tonne units placed in a single row
(Figure 13). The packing density of the 11-tonne Core-Locs was 0.62. Toe pro-
tection units were placed 90 deg to the toe units of the structure in a manner in
which adjacent units interlocked (Photos A23 through A25). The 11-tonne Core-
Locs used for toe protection were displaced during 13- and 16-sec, 3.7-m waves,
and the armor layer failed due to toe instability (Photos A26 and A27).
Plan 2A
Plan 2A was the same as Plan 2 except the single row of 11-tonne Core-Locs
was replaced with a wood board anchored to the floor around the entire Core-
Loc armor layer to act as an immovable toe restraint. The board simulated a toe
trench 1 m deep and included a 45-deg bevel adjacent to the toe unit (Figure 14).
The plan consisted entirely of 11-tonne Core-Locs ( = 0.61) beginning at
Profile 4 with a crest elevation of +8 m CD throughout the structure (Photos A28
through A30). One toe unit was displaced during 16-sec, 3.7-m waves near
Profile 5, but the structure was stable for waves up to 16-sec, 5.2-m waves.
During the 16-sec, 5.2-m condition, one toe unit was displaced near Profile 6,
one toe unit was displaced from Profile 9, and three toe units were displaced
near Profile 10. No further displacement of Core-Locs was observed for 19-sec,
5.2-m or 13-sec, 6.7-m waves; however, underlayer stone was observed to be
displaced between Profiles 4 and 6 in areas of toe displacement. Additionally,
the armor layer began to loosen in this area. During 16-sec, 6.7-m waves,
16 additional toe units were displaced, producing noticeable damage to the struc-
ture. Most of the armor was displaced off the structure at the elbow between
Profiles 8 and 9 during 19-sec, 6.7-m waves (Photos A31 through A33).
19
Chapter 3 Results
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