Descriptions and Test Results for the Concrete 

 Block Plans 



Plan 4 (Figure 7) used the same overall geometry (crown elevation, crown 

 width, and armor slopes) as previous plans tested at the -8.6-ft erosion depth. 

 However, the 5-ton armor stone was replaced by 6.2-ton concrete blocks (spe- 

 cific weight = 150 pcf). The 2.5-ft-thick, 5.5-ft-wide, and 6-ft-long blocks 

 were uniformly placed with their least dimension perpendicular to the slope. 

 Also, in an effort to reduce toe and shore-side crest stone movement, the 200- 

 to 1,000-lb stones were replaced by 200- to 2,000-lb material. Plan 4 was 

 tested with the same wave conditions used in tests of Plan 3 (Table 3). 



SEA SIDE 



LAND 



SIDE 



+7 FT MLT^ 

 2.5 ^-"^, 



w 2 



— +5 FT MLT 



~P~2X— _ 



*"~ S 



-8.6 FT MLT 1 ^> ^^i^^^^ 



\ -5 FT MLT —/ rAr>r<^-^^^ 



EXISTING EMBANKMENT 

 (ASSUMED STABLE) 



\ -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 7. Concrete block revetment cross section, Plans 4 and 4R 



Seaward slippage of the 6.2-ton toe blocks was initiated at the +4.0-ft swl. 

 Also, as the toe blocks moved slightly seaward, the next five rows of blocks 

 above them packed downslope. This left a gap of about 6-9 in. (prototype) 

 between the upper row of slope blocks and the first row of crest blocks. Sev- 

 eral of the seaside blocks were observed to lift slightly during wave attack; 

 however, none were displaced. A small amount of additional slippage of the 

 seaward blocks was observed during the +7.0- and +9.5-ft swl's (the above- 

 described gap was about 10 in. wide by conclusion of the +9.5-ft swl). Con- 

 tinued lifting and reseating of the blocks was observed at the +14-ft swl, with 

 one block being displaced downslope during step 24 (Table 3 at the -8.6-ft mlt 

 toe condition). Photos 13 and 14 show the section after wave attack. The gap 

 between the upper row of slope blocks and the first row of crest blocks was 

 about 1 ft (prototype) at the conclusion of the test. The stability response of 

 the concrete blocks in Plan 4 is considered marginally acceptable. 



Chapter 3 Tests and Results 



11 



