and Jarlan (1968) suggest. Because of this, the following relationship 

 was used: 



(H^)2 



= 0.64 



This gives H^ = 0.8H^. 



The general Sainflou method was then used to compute the wave forces 

 on the structure (Jarlan, 1961) . 



A reduction factor for wave pressure can be applied when computing 

 resultant forces on a breakwater section 250 feet long or longer, 

 because the maximum pressure occurs at the same time only over compara- 

 tively small structure lengths for the irregular wind waves experienced 

 during hurricanes. However, for the present study, no reduction factor 

 has been applied. 



4. Calculations . 



Sample calculations for the concrete caisson in 110-foot water depth 

 are given in the Appendix. Dimensional details of the caisson are shown 

 in Figure 1 . 



The concrete units were proportioned for water depths ranging from 

 50 to 110 feet, both with and without oil storage capabilities. 



The results of these studies are shown in Figure 2. 



5. Review of Results . 



The analysis shows that the units required for the oil storage and 

 nonoil storage alternatives in either 90- or 110-foot water depths are 

 basically the same size regardless of depth. The size is dictated by 

 the required safety factor against sliding and on allowable soil-bearing 

 pressures. 



The design wave force determines the minimum weight and base width 

 of the unit. The width required for stability provides enough space for 

 oil storage compartments. The units can be designed to provide additional 

 oil storage. 



Increasing the base width above the minimum width established by the 

 force exerted by the design wave will in effect reduce the soil pressure 

 and increase the safety factor. 



For installations where units are to function primarily as a break- 

 water without oil storage, the leeward face can be perforated to reduce 

 reflected wave action within the harbor. However, when the units are 



13 



