where Lj is the wavelength in a depth equal to dg, and m is the near- 

 shore slope. The forces and moments resulting from the hydrostatic pres- 

 sure must be added to the dynamic force and moment computed above. The 

 triangular hydrostatic pressure distribution is shown in Figure 7-74; the 

 pressure is zero at the breaker crest (taken at Hj,/2 above the SWL) , 

 and increases linearly to wCdg + H^/2) at the toe of the wall. 



The total force is 



"!,\' 



R. = R^ + ^— = R« + R, , 



(7-80) 



and the total moment about the toe is. 



»i\' 



M, = M^ + — ^ '— = M^ + M^ 



t m /■ m s 



(7-81) 



The last terms on the right side of Equations 7-80 and 7-81 (Rg and Mg) 

 are the hydrostatic contributions. 



Pm 



SWL 





^: 



-' "Dynamic Component 



Hydrostatic Component 

 X^^ Combined Total 



— w(ds-f^) — 

 Figure 7-74. Minikin Wave Pressure Diagram 



Calculations to determine the force and moment on a vertical wall are 

 illustrated by the following example. 



************** 



EXAMPLE PROBLEM ******** 



****** 



GIVEN : A vertical wall, 14 feet high is sited in sea water with dg = 7.5 

 feet. The wall is built on a bottom slope of 1:20 (m = 0.05). Reasonable 

 wave periods range from T = 6 sec. to T = 10 sec. 



7-147 



