Plan 7 was subjected to the 20-step test given in Table 7. Slight seaward 

 shifting of the first row of concrete blocks was initiated at the +4-ft swl. As 

 the toe blocks shifted seaward, the six rows of onslope blocks packed down- 

 slope, leaving a gap between them and the three rows of crest blocks. This 

 slow progressive movement continued through the +7-ft swl. At the conclu- 

 sion of testing, the gap between the slope and crest blocks varied from a few 

 inches to about 1.5 ft (prototype). Individual concrete blocks appeared to be 

 hydraulically stable, i.e., no lifting or displacement was observed. Photos 31- 

 33 show the overall condition of the section after wave attack and Photo 34 

 shows details of the block separation. 



Plan 7R (Figure 1 1) was a rebuild of Plan 7. Subjection to the 10-step 

 hydrograph given in Table 7 verified results of the first test, i.e., a gap, vary- 

 ing in width from a few inches to 1.5 ft, developed between the slope and 

 crest blocks as a result of toe slippage and subsequent downslope slippage of 

 the slope blocks. Again, no lifting or displacement of individual blocks was 

 observed. Photos 35-38 show the final condition of the test section. As can 

 be observed in after-testing photos, the 200- to 2,000-lb toe and crest stone 

 experienced some displacement. 



Plan 8 (Figure 13 and Photos 39 and 40) was the same as Plan 7, except 

 that the toe stone weight was increased to 200 to 4,000 lb in an effort to 

 improve its stability and hopefully reduce sliding of the concrete blocks. Sub- 

 jection to the same wave conditions as Plan 7 produced improved results; i.e., 

 the toe stone was stable and the maximum gap between the slope and crest 

 blocks was reduced to about 1 ft (prototype). Photos 41-44 show the structure 

 after wave attack. 



SEA SIDE 



LAND 



SIDE 



+ 7 FT MLT^ 

 2.5 .^-""'S 



W 3 



— +5 FT MLT 



I "■£*<--» 



'" — -/ 



W lW. i|^^^<^-^' 



-5 FT MLT — / rVCV^^^' 



/ w 2 J-H^^ 



EXISTING EMBANKMENT 

 (ASSUMED STABLE) 



\ -10.0 FT MLT 







MATERIAL CHARACTERISTICS 







W, = 6 TON OPTIMIZED CONCRETE BLOCKS 







W 2 = 200-4000 LB STONE 







W 3 = 200-2000 LB STONE 



MODEL SCALE 1 



24 



W 4 = 1-200 LB STONE 







Figure 13. Optimized concrete block revetment cross section, Plans 8 and 8R 



16 



Chapter 3 Tests and Results 



