Crest of Clapotis 



Figure 7-98. Pressure distribution on wall on rubble foundation. 



where M" is the moment about the bottom (point A on Fig. 7-98). 

 the momenx desired is that about point B , which may be found from 



^bM^-'^J^-' P- V)' 



or 



Usually, 



(7-84) 



1^ = M^ - bF" 



The values of (1 - r ) and (1 - r^) may be obtained directly from Figure 

 / — y / . 



************** EXAMPLE PROBLEM 33 *************** 

 GIVEN ; 



(a) A smooth-faced vertical wall on a rubble base. 



(b) Height of rubble foundation, b = 2.7 m (9 ft). 



(c) Incident wave height H- = 1.5 ra (5 ft). 



(d) Design depth at the structure d = 3m (10 ft). 



(e) Wave period T = 6 s (minimum) or 10 s (maximum). 



FIND ; The force and overturning moment on the given wall on a rubble 

 foundation. 



SOLUTION ; For this example problem Figures 7-90 through 7-92 are used to 



7-178 



