The 200-m distance, therefore, translates to 



y = 200 ^ 



L 92 ^'^' 

 At 200 meters, the wave height should be 1 meter. 



"l = K,(6) 

 1 = V6) 

 K = 0.167 

 From Figure 7-61 



X = (8) (92) 



X = 736 m say 750 m 



required breakwater length = 750 m . 



4. Preliminary Design of Quay Wall Caisson . 



Since the quay will be protected by breakwaters after construction is 

 complete, the caisson will experience extreme wave action only during 

 construction. For illustrative purposes the following conditions will be used 

 to evaluate the stability of the caisson against wave action. It should be 

 noted that these conditions have a low probability of occurrence during 

 construction. 



Hg = 3.59 m 



H = 6.0 m 



Tg = 7.78 s 



d = 12.0 + 1.5 ^ 



d = 13.5 m 



Note that the bearing area for the quay wall acting on the foundation soil 

 may be reduced by toe scour under the edge or by local bearing capacity 

 failures near the toe when the foundation pressure there exceeds the soil's 

 bearing capacity. 



Further information on this problem may be found in Eckert and Callender, 

 1984 (in press) or in most geotechnical textbooks. 



Probability of extreme surge during construction is assumed negligible. 



8-75 



