indentations might be advantageous in the lifting and placing of blocks during 

 construction. 



Testing of Plans 1-6 showed wave conditions for the -8.6-ft mlt erosion 

 depth to be significantly more severe than those observed at the -3.6-ft depth; 

 therefore, stability tests for Plans 6 and 6R were conducted only at the -8.6-ft 

 depth and it was assumed results could be conservatively applied to any lesser 

 depth. Plan 6 was subjected to the 16-step test given in Table 5. The concrete 

 blocks proved to be stable for all wave conditions; however, a few of the 

 smaller 200- to 2,000-lb shore-side crest stones were displaced (Photos 25-27). 



Plan 6R (Figure 9) was a rebuild of Plan 6. It was tested to verify the 

 stability response of the modified concrete blocks. Subjection to the abbrevi- 

 ated worst case hydrograph given in Table 4 produced the same results as the 

 initial test, i.e., no movement of the concrete blocks was detected for any of 

 the wave conditions. Photos 28-30 show the final condition of the test section. 



The concrete blocks used on Plans 6 and 6R appeared to be conservatively 

 stable. Therefore, in an effort to reduce cost without sacrificing stability, the 

 blocks were redesigned with a 2.5-ft thickness and a slightly increased porosity 

 (approximately 4 percent). 



Plan 7 (Figure 11) was armored with the new 6.0-ton concrete blocks. The 

 2.5-ft-thick, 5.75-ft-wide, and 5.75-ft-long blocks (Figure 12) were uniformly 

 placed with their least dimension perpendicular to the slope. The toe and 

 splash apron were protected by 200- to 2,000-lb stone. 



sea side: 





LAND SIDE 



+ 7 FT MLT^ 

 2.5 ^--^O 



w 





l-Ex^-, 





— +5 FT MLT 



-— -y 





1 ^ i-^^^ 



EXISTING EMBANKMENT 

 (ASSUMED STABLE) 







MWA 



1 >^^w v 3 



w 2 ) -^^ 1 



-9.5 FT MLT 







MATERIAL CHARACTERISTICS 







W, = 6.2 TON CONCRETE BLOCKS 







W 2 = 200-2000 LB STONE 



MODEL SCALE 



1 :24 



Wj = 1-200 LB STONE 







Figure 8. Concrete block revetment cross section, Plans 5 and 5R 



Chapter 3 Tests and Results 



13 



