/ . - 



The free-fall-emplaced deadweight anchor system is also usable on 

 soil seafloors in the Gulf Stream environment, provided that the sea- 

 floor is sufficiently compliant to ensure landing and complete embedment 

 of the shear keys without the occurrence of structural distress in the 

 anchor. Rather than using one very large anchor to resist the 180-MK 

 (40 X 10 -lb) ultimate lateral load, multiple free-fall deadweight 

 anchors, weighing about 20 UN (5 x 10 lb) submerged each, would pro- 

 bably be used. Individual mooring lines would connect the plant to each 

 anchor with load among lines equalized by an automatic system on the 

 plant. 



Pile Group. The seafloors at some potential OTEC power plant 

 sites, notably some of those in the Gulf Stream adjacent to the U. S. 

 coast, will be locally uneven and noncompliant or hard (rock-like). A 

 deadweight anchor is not efficient in developing lateral load capacity 

 on such hard seafloors. Further, a free-fall-emplaced deadweight anchor 

 will very likely suffer serious structural damage if landed on an unyield- 

 ing, rock-like seafloor. In these local areas of near-surface or exposed 

 hard material, an anchor incorporating piles will often provide the 

 desired anchor holding capacity with far less material weight and pro- 

 bably at lower cost (neglecting technology development costs). 



The vertical component of mooring line load and overturning forces 

 on the pile cap/framework would be resisted by tension piles 0.4 to 

 0.8 m (15 to 30 in.) in diameter by AO m (130 ft) in length (Figure 6). 

 The horizontal load component would be resisted by short, large diameter 

 stub piles acting much like shear pins between the pile cap and the rock 

 mass. Quite likely, the upper ends of the tension piles will be reamed 

 out to serve as the "shear piles," as shown in Figure 6. < • 



Installation of the pile group anchor would be carried out by first 

 lowering a 4-MN (1 x 10 lb) submerged framework to the seafloor. 

 Lowering of this framework in 500- to l,000-m (1,500 to 3,000-ft) water 

 depths would be handled by a crane barge or possibly by a drillship 

 (Figure 4). The framework would initially serve as a guide during pile 

 installation. After the pile shells had been grouted into the guides, 

 the framework would serve to distribute the mooring force from the 



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