' T = S.^- seconds = wave period, 



d = 26 feet = depth of water below datum at the structure. 



The wave direction is normal to the breakwater. The depth of water being 

 twice the wave hei:^,ht, the waves will not break on or before the structure 

 and the Sainflou method for computing wave pressures from non-breaking 

 waves can be used. The pressure diagram developed by this method is 

 shown in Figure 129. 



El. + 18' 





H=I3.0 / 









/ 





still water level 



h= 4.6' 



\ /o 



■ H= 13.0' \ 







If Va.4' 



^— X-- 30.0 ' — > 







- 26 



- 32 



nc^/~rnrh 



^^5^^)^^^^^^^^^^^^*^^^-%:^ 



FIGURE 129 -PRESSURE DIAGRAM FOR CAISSON TYPE BREAKWAIbR 



393. The height (hg) of the mean level of clapotis (orbit center) 

 above the still water level, is taken from the graph, Figure 75 using the 

 value of 2d/L = 2(26) =0.3/i6. In like manner the value of P-|_ is taken 



150 

 from Figure 76. (See pages 103 and lOU) 



ho = ^.6 feet 



P-i = 490 pounds - the pressure the clapotis adds or substracts 

 from the still water pressure. 



The upper and lower limits reached by the clapotis are 



hg + H = 4.,6 + 13 = 17.6 feet above still water level. 



191 



