The University of Rhode Island has observed the settlement of simulated 

 pipe sections on bay sediments. Results are to be compared to predicted values 

 (Nacci, 1969). 



Habitats 



A number of manned habitats (Table 3) have been deployed on the 

 seafloor. General observations of their performance are available. Other habi- 

 tats are in the design or fabrication stages. I n these cases, the detai Is of the 

 selected foundation systems are useful as case histories, since the systems 

 display the thinking of the designer relative to his past experience and 

 knowledge of foundation performance. 



Habitats represent a somewhat specialized set of case histories for 

 several reasons. To date, the deepest deployment of a habitat for which any 

 information is available has been 328 feet. Site selection for such deployments 

 is usually heavily influenced by the requirement for good diver visibility. This 

 requirement typically results in selection of sandy sites. In addition, considera- 

 tion of the consequences of any sort of foundation failure (in terms of possible 

 loss of human life) usually leads to an extremely conservative approach to site 

 selection and foundation design. The following sections summarize some of the 

 pertinent characteristics of various habitats. 



Conshelf One. During September of 1962, an 8-foot-diameter by 

 1 7-foot-long steel cylinder was anchored horizontally in the Mediterranean 

 near Marseilles, France (Cousteau, 1963). Conshelf One (Continental Shelf 

 Station One) became Captain Jacques Yves Cousteau's first in a series of 

 manned underwater habitats. The station, which housed a crew of two men 

 for a week at a water depth of 33 feet, experienced no foundation problems. 



Conshelf Two. Cousteau placed his second underwater manned 

 station, Conshelf Two (Figure 24), in June of 1963 (Cousteau, 1964). Con- 

 shelf Two was located in the Red Sea approximately 5 miles northeast of Port 

 Sudan. The main structure, Starfish House, sheltered five men for a month at 

 a depth of 36 feet. Five telescopic legs with 4- by 4-foot bearing plates sup- 

 ported Starfish House on a coral sand ledge. Lead ballast of 200,000 pounds 

 was added to the habitat to provide negative buoyancy. During Conshelf Two, 

 Deep Cabin, a 20-foot-long rocket -shaped underwater chamber, housed a 

 two-man crew for a week at a depth of 80 feet. Although three telescopic 

 legs with bearing plates were intended for support, extremely steep rocky 

 terrain precluded their use. Instead, the Deep Cabin was anchored on the 

 steep slope. A third structure, the diving saucer hangar, allowed Cousteau's 

 diving saucer to operate from a dry base 36 feet below the water surface. 



39 



