When e, the lever arm of the load applied above the firm bottom, is 

 zero the equation may be solved directly for required pile length as: 



I = 



U dk J 



1/2 



(8) 



This method of analysis has been predicated on the maximum bending 

 moment in the loaded pile not exceeding the piling sections maximum yield 

 moment. This is considered a safe assumption for the typical short anchor 

 pile problem. 



When the foundation soils at the breakwater site are clay, the method 

 in Broms (1964a) is used for determining the ultimate lateral resistance 

 of a rigid-pile anchor under lateral load. As before, the pile is assumed 

 to rotate without bending around a point in the lower half of the pile 

 (see Fig. 6). The length of pile required is 



e+1.5D+f+q 



(9) 



(See Fig. 6 for definition of terms.) The maximum moment occurs at 

 (f + 1.5D) below the firm soil level where 



f = 



(10) 



9 c u D 



The term c is the undrained cohesive strength of the clay. Care 

 should be taken in the determination of the value of c to reflect the 

 dynamic nature of the lateral load. The length, q, is the length of 



Figure 6. Failure mode for a short-rigid pile in 

 cohesive soil (after Broms 1964a). 



