deficiencies already identified by the Navy. As an example, the 

 study has shown which direction to take in habitat power develop- 

 ment. It indicated that an umbilical power link from shore will be 

 most cost effective for habitats less than about 100 miles from 

 shore. For other habitats nuclear power will be required. It also 

 identified knowledge of the behavior of marine sediments as a criti- 

 cal technology restraint. 



For several years we have been conducting research to bridge 

 the gap between terrestrial soil mechanics and what can be termed 

 "mechanics of marine sediments". An example of one of the ques- 

 tions we have answered through laboratory research is that hydro- 

 static pressure appears to have only a minor effect on the strength 

 of marine sediments. In-situ measurements are necessary to vali- 

 date laboratory measurements. Sediments fornaing in a seawater 

 environment tend to have a flocculated grain structure which ex- 

 hibits large changes in strength when disturbed. Besides the dis- 

 turbance inherent in sampling, a sample undergoes a large change 

 in pressure (which may affect interparticle bonds as porewater 

 and gas expand) and transport disturbance before strength tests 

 are performed in the laboratory. A deep-ocean sediment test sys- 

 tem has recently been developed which may be used to make in-situ 

 measurements of the engineering properties of marine sediments 

 to depths of 6000 feet. Initially it has been equipped with a vane 

 shear device, cone penetrometer and other simple work sys- 

 tems. Developments underway for this system include a 30- foot 

 coring capability and instrumentation for determining seismic 

 activity and turbidity potential. 



Although progress is being made in seafloor engineering, many 

 deficiencies, such as sediment stability, seismic response, ex- 

 cavation, ingress, and renaote power have only recently been 

 addressed. Because of the limited development in seafloor engi- 

 neering and the eventual requirement for this capability for any 

 effective ocean resource utilization, this is one of the most chal- 

 lenging and potentially rewarding technology areas in ocean en- 

 gineering. 



Environmental Support 



Objectives in environmental support of ocean engineering are 

 to develop feasible solutions to the problems of measuring the 

 undersea, atmosphere, and interface environment, predicting it, 

 and influencing it. In order to effectively plan and execute any 



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