Rubble-Mound Dike, 1991 Profile 



Model construction 



Modeling of the rubble-mound dike assumed the prototype would be 

 constructed with an impermeable core covered by an underlayer and two 

 layers of armor stone. The model rubble-mound dike was constructed of a 

 piece of plywood for the impermeable core with crushed gravel retained 

 by a No. 6 sieve glued to the board to simulate the underlayer. Crushed 

 gravel passing a 3/4-in. sieve and retained by a 5/8-in. sieve was used for 

 the armor stone. Average weight of the armor stones in the model was 

 0.022 lb (672 lb prototype). 



The toe wall used for the park dike was used again for the rubble- 

 mound dike but repositioned further back from the seawall on the assump- 

 tion the mound would be built on the west side of the existing Revere 

 Boulevard. Crest height of the impermeable core was set at +25.4 ft mlw. 

 The rubble mound was constructed to the dike crest, and the area behind 

 the crest was sealed to retain the overtopping (Figure 15). 



+25.4 



Rubble-Mound 

 Dike 



h 



+21 .5 ft 



Sea- 

 wall 



-21.3 ft 



Concrete Slope in Wave Flume 

 All elevations 



in feet mlw 





Figure 15. Cross section of rubble-mound dike 



A seawall crest elevation of +21.3 ft mlw was used for all tests because 

 it was observed in the park dike study that this crest elevation produced 

 more overtopping than the lower crest elevation. 



Test conditions and results 



Generally, the same test conditions used in the park dike study were 

 used for the rubble-mound dike. Still-water level was at +16.6 ft mlw, 

 and beach elevation was set at +20.5 ft mlw. Test conditions and overtop- 

 ping rates are listed in Table 16. 



Tests 12 and 13 used a peak wave period of 13 sec and H^^s of 10.0 

 and 12.7 ft, respectively. There was no overtopping in either test. 



50 



Chapter 5 Revere Dike Study 



