Long pile analysis lateral load capacities for various lengths and 

 diameters are shown as dashed curves in Figures 19, 21, and 22. A long 

 pile analysis was not done for category B soil (Figure 21). Curves were 

 drawn through the more conservative capacity at the transition length 

 between the long and short pile analysis, i.e., at Z = 10 x D. The 

 solid and dashed lines delineate the lateral capacity envelope for the 

 piles shown. 



Results . Review of Figures 19 and 20, indicative of pile anchor 

 performance in deep ocean environments, suggests that single piles of 

 7.6 m diameter (25 ft) and 47 m in length would be required to mobilize 

 the necessary 18 MN (4x1 0^ lbs) lateral load resistance. 



Figures 21 and 22, indicative of performance in a competent clay and 

 sand seafloor, as might be found beneath a high energy area, suggests 

 that a single pile anchor design is probably not appropriate for such an 

 area. Piles of 7.6 m diameter (and of the stiffnesses assumed) are not 

 capable of resisting the full 130 MN horizontal load component (40x10" lbs). 

 Larger diameter piles could mobilize sufficient soil resistance to resist 

 the Gulf Stream loading, however, technical feasibility suggests that a 

 multiple pile anchorage using smaller piles would be more reasonable. 



Figure 23 illustrates the influence of the pile analysis procedure 

 employed. The short pile analysis assumed mobilization of the available 

 soil resistance and maximum bending moment in the short piTe was calcu- 

 lated. Then a pile section was designed to resist that moment. This 

 pile section was then input into the long pile analysis (or more properly 

 the stiffness values were input). This fixing of the pile stiffnesses 

 results in the fixing of the bending resistance of the respective pile 

 diameters. For lengths greater than about 10 diameters; lateral load 

 capacity is controlled by the assumed bending resistance. Adherence to 

 this procedure is justified because the pile secitons designed appear 

 practical as is: increasing the pile stiffnesses would result in verv 

 thick-walled, unreasonable, possibly unfabricatable sections. The actual 

 pile sections designed will be presented and discussed later; it is 

 important to note here that the break in the lateral load capacity curve 

 (Figure 23) is not indicative of a soil phenomenon, but rather is due to 

 the pile stiffness assumed in the analysis. The data presentation of 

 Figure 23 suggests that for the pile sections used, there is no marked 

 improvement in lateral load capacity when the pile is lengthened beyond 

 10 diameters. However, increasing the length beyond 10 diameters may 

 decrease pile deflection. Figure 24 shows deflection at maximum load 

 for the 8 ft. diameter pile at Z = 10D and Z = 20D. The figure indicates 

 much larger deflection at the shorter length. At Z = 10D, the pile is 

 definitely exhibiting the short pile behavior idealized in Figure 18. 

 Increasing length to 20 diameters gives the smaller deflections charac- 

 teristic of long pile behavior (Figure 17). At 30 diameters length 

 deflections would be almost the same as the 20 diameter case. The point 

 at which increases in length do not give a corresponding decrease in 

 deflection depends on a well-known stiffness factor (Gill and Demars, 

 1970, and others): 



50 



