INTRODUCTION 

 Objective 



The objective of this effort was to collect and summarize all available 

 information on the performance of seaf loor foundations. This information, 

 along with an analysis, was directed at understanding the parameters which 

 affect performance and establishing guidelines for more effective foundation 

 design. 



Scope 



This summary of foundation performance is incomplete, because the 

 collection and analysis efforts are to be continued. Often the only available 

 knowledge of performance is that the foundation exists and that it either did 

 or did not apparently function satisfactorily. Efforts are continuing in the 

 collection of more detailed information on installations discussed here and 

 additional information on installations which may have been missed in this 

 initial study. 



Background 



The Navy is currently utilizing numerous ocean-bottom installations 

 which depend upon the seafloor soils for their support (positive, negative, 

 and lateral). These installations include offshore towers, habitats, and 

 bottom-sitting test structures on the continental shelves. Test structures 

 and a surprisingly large number of acoustic arrays and similar devices located 

 in the deeper oceans constitute the remaining portion of seafloor installations. 

 All of these seafloor structures, or installations, require some form of founda- 

 tion through which vertical and horizontal forces are transmitted to, and 

 resisted by, the seafloor. 



A number of the foundations now in use have experienced difficulties- 

 performance was sufficiently unsatisfactory to impair the mission of the 

 installation. A few foundations have been involved in failures which have 

 required remedial measures. 



