Table 2-3. a correction factor for multiple layers 

 of armor units. ^ 



^Derived from data with cot 8 = 2.5, d /d^ = 0.15, 

 0.004 < d„/gT2 < 0.03. 



*************** EXAMPLE PROBLEM 14*************** 



GIVEN : A wave with a period T = 10 seconds and a height H^ = 2 meters (6.56 

 feet) impinges on a revetment having two layers of armor units with diameter 

 d = 1 meter (3.28 feet). The structure slope is cote = 5; the breaker 

 height is H^j = 3.60 meters (11.8 feet); the wavelength at breaking is Ljj = 

 65.2 meters (214 feet). 



FIND: Determine the reflection coefficient. 



SOLUTION; Calculate the dimenslonless parameters 



/dg/L cote - V 1/65.2(5) = 0.62 





2.0 

 3.60 



= 0.56 



and 



_i. = il£= 5 

 H. 2.0 "-^ 



X 



From Figure 2-66 with \/d /L cot9 = 0.62 and ^/H^ = 0.56, read a^ = 0.29. 



From Table 2-3 with d /H^ < 0.75 and n = 2, read a^ = 0.93. The reflection 



coefficient x = 0.29 from the earlier example for a smooth slope is multi- 

 plied by a and a so that 



X = ai ci2 (0.29) = (0.29)(0.93)(0.29) = 0.08 



2-121 



