sixteen-pod configurations. The use of steel cylinders for the sixteen- 

 pod configuration results in undesirably thin cylinder walls. In the 

 sea, corrosion would considerably reduce the percentage of steel section 

 remaining and, as a result, considerably reduce the load capacity; thus, 

 cathodic protection of the cylinders would probably be required. Be- 

 cause of this complication, the steel, sixteen-pod configuration was 

 deemed undesirable. Other factors which may well prove determining, 

 such as the effect of non-uniform load on a pod and the influence of 

 lateral loads, are not amenable to analytical evaluation. However, 

 based on this analysis it does appear that diametrically-loaded crush- 

 able cylinders are more practical than axially-loaded ones. 



The concept of a crushable foundation deforming to shape itself 

 over microrelief leads to another variation: consider a foundation 

 underlain by an initially deformable material which first conforms to 

 the seafloor surface and then later becomes rigid or "sets-up" as 

 concrete. The setting materials could be grouts or plastics; the 

 material could be contained beneath the foundation plate by a single 

 membrane, by a number of sacks, or could be contained in a variety of 

 reticulated foam. Reticulated foam is employed in military aircraft 

 fuel tanks; the fuel can be pumped out of the tank, but it will not 

 flow out under the influence of gravity. 



In summary, it is feasible to fabricate a foundation having a 

 crushable bearing surface that will accommodate a rock surface of con- 

 siderable irregularity. Preliminary analysis indicates that PVC 

 cylinders standing on their ends and PVC and steel cylinders lying on 

 their sides will perform satisfactorily as the crushable elements. 

 Other material/system concepts, which may also serve as a crushable, 

 rigid element, but which are not sufficiently developed for present 

 use, are a rigid, open-cell foamed plastic material and a grout with 

 adjustable gel time contained beneath the foundation in flexible con- 

 tainers or in a reticulated foam. 



Deadweight Anchor 



A deadweight anchor or clump anchor may be as simple as a cube of 

 concrete or an oblong slab of rock with an eye-ring set in for 

 attachment. The AFAR tower foundation described earlier is essen- 

 tially an eight-foot-square steel deadweight anchor with a universal 

 joint linking it to the 120-foot tower above; the four pointed steel 

 feet serve to increase resistance to lateral sliding on the hard rock 

 surface. For more compact installations, it is possible to modify the 

 AFAR concept by adding a universal joint that "freezes" through cor- 

 rosion or an explosive lock, thereby holding the installation rigid 

 relative to the clump. The deadweight anchor may be further altered 

 into a "coral" anchor by adding prongs, teeth, or appendages to engage 

 the rock surface and increase resistance to lateral movement. However, 

 depending on the environment, the clump characteristics, and the instal- 

 lation characteristics, the unit may rock considerably. Deadweight 



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