(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 All 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. 



PlanIB 



Plan IB 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 (p = 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. 



PlanIC 



Plan 1C was the same as Plan IB 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 



1 6 Chapter 3 Results 



