268. The Minikin relationvships for shock press\ires, thrusts, and 

 overturning moments due to wave action are: 



?^ = lOlw H^/Lq d(l+d/D) for maximum pressure (55) 



Rj^ = PjTi X H^/3 for total thrust per foot of wall (56) 



Mj^ = Rfn X (d+2) for overturning moment (note that (57) 



the moment arm is d + 2 since the wall 

 base is 2 feet below ultimate ground 

 level) 



where Lq and D may be determined as follows for tiie 7 and 9-second wave 

 periods with d = 10 feet. Values for d/Lj) for the various values of d/Lo 

 may be taken from Table 1, Appendix D. 



TABLE 16 - Determination of D and Ln 

















CD (2; (3") 



Period T Lq d/L^ 



(U) 

 d/Ld 



Ld 



(6) 



(,7) 



D/Lo 



(9) 



Ld 



(seconds) (feetj 



7 251 o.oUo 

 9 Ul5 0.02U 



0.083 

 0.063 



(feet) 



120 

 160 



(feet) 



16 

 18 



0.06U 

 0.0U3 



0.11 

 0.087 



1U5 



207 



269. Therefore the shock pressures, thrust, and moments about the 

 base due to the 7 and 9-second waves respectively are given in Table 17» 



TABLE 17 - Shock Pressures, Thrusts and Moments 













Period T 



Breaker 

 Height Hq 



Pressure 



Thrust 



Moment 



( seconds ) 



7 

 9 



(feet) 



9 

 10 



(lbs. per sq.ft.) 



65i;0 

 U86O 



(lbs. per sq.ft.) 



19,620 

 16,200 



(ft.-IDDVft.) 



236,000 

 19U,500 



270, Since the wall is to be founded 2 feet beloxiT the ultimate 

 ground line, the static forces on the face of the wall due to viave action 

 may be computed as that force due to a head of water of height (d + 2 + H/2), 

 Therefore, the maximum static pressure will occur at the wall base (the 

 depth d^) and is given by 



P^ ^ ;v(d+2+H/2) (58) 



the total thrust per linear foot of wall is given by 



133 



