FIND : 



(a) The maximum pressure, horizontal force and overturning 

 moment about the toe of the wall for the given slope, and 



(b) the maximum pressure, horizontal force, and overturning 

 moment for the 6-second wave if the slope were 1:100. 



SOLUTION : 



(a) From the example problem in Section 7.122, the maximum breaker 

 height for a design depth of 7.5 feet, a slope of 0.05, and wave 

 periods of 6- and 10-seconds are 



Hy = 8.4 ft., (T = 6 sec.) 



Hj, = 9.8 ft. (T = 10 sec.) 



The wavelength at the wall in water 7.5 feet deep can be found 

 with the aid of Table C-1, Appendix C. (The following calculations 

 are for the 6-second wave.) First calculate the wavelength in 

 deep water (T = 6 sec), 



L = — = 5.12(6)2 ^ 184 ft. 

 " 27r 



Then 



d 7.5 



— = = 0.0408, 



Lo 184 



and from Table C-1, Appendix C, 



d 



— = 0.084, 

 L 



and 



. L^ = 89.1 ft. 



From Equation 7-79 



D = d^ + L^ m = 7.5 + 89.1 (0.05) = 11.96 ft., 

 and using Table C-1, as above, 



D D 



— = 0.0650 ; — = 0.1091, 



hence 



say 



^/■•c 



Ljy = 110 ft. 



11.96 



= 109 ft., 



0.1091 



7-148 



