Construction Details 



The structure dimensions (crest width, layer thicknesses, etc.) are calculated 

 based on equations presented in SPM (1984). Crest width calculated by 

 Equation 6 is 15.8 ft 



B = nks 





(6) 



where 



B = crest width in ft 



n = number of units in width (recommend minimum value of 3) 



kji = layer coefficient (equals 1 for 2-layer, rough quarry stone) 



W = armor unit weight ( 1 2 tons) 



y,. = unit weight of armor unit in Ib/cu ft (assume equals 165 Ib/cu ft) 



Armor layer thickness calculated by Equation 7 is 10.5 ft. 



nkA 



V, 



where 



r = average thickness of armor layer in ft 



/; = number of units in thickness (assume has a value of 2) 



The number of armor units per surface area calculated by Equation 8 is 4.6 

 per lOOft^ 



A [ ioo){ir) 



where 



N,. = number of units per given surface area 



A = surface area 



P = porosity (equals 37 percent for 2-layer. rough quarry stone) 



The primary underlayer stone size is ff/1 or 1 .2 tons (range of 1 .0 to 

 1 .4 tons), and the bedding layer ranges from fr/4000 to W/20Q (approximately 6 

 to 120 1b). 



Plan and profile views of the 100-ft extension to Groin 44 are shown in 

 Figure 40. Sections along the groin length and across the groin width are shown 



Chapter 4 Structure Design 



51 



