INTRODUCTION 



It is expected that future Navy seafloor and subsurface installa- 

 tions will require foundations and anchorages of greater capacity and 

 reliability than are provided by the foundation or anchorage systems 

 ordinarily used (e.g., spread footings, mats, dead-weight anchors, and 

 drag-type anchors). Piles and pile groups can often be designed to 

 provide the required increase in capacity and reliability. However, 

 the Navy has no means for emplacing piles in water deeper than about 

 100-150 feet. Few commercial organizations can emplace piles in water 

 depths beyond 150 feet, and these operations are very expensive. Since 

 further seafloor and subsurface installations frequently will be in 

 greater water depths it will be necessary to develop economical means 

 of emplacement to permit the use of piles for these installations. 



Background 



A review of the state-of-the-art of seafloor pile emplacement has 

 shown that only marine drilling techniques could be adapted to emplace 

 piles or pile groups for an immediate requirement in water deeper than 

 1000 feet. 2 Pile emplacement using other state-of-the-art methods (e.g., 

 underwater pile hammers and vibrators or surface-driving with followers) 

 is currently limited to about 1000 feet by logistics problems. However, 

 only moderate effort is required to develop a pile emplacement system 

 operable to 6,000 feet. Three existing mechanical concepts were shown 

 to be possible candidates for further development: vibratory drivers, 

 screw piles, and jack-in piles. 



Scope 



In this report conceptual designs for pile emplacement systems 

 based upon each of the three mechanical concepts are presented, and 

 the advantages and disadvantages of each are summarized. A comparison 

 of the advantages and disadvantages led to the selection of screw 

 piles as the best system for further development. A preliminary design 

 is presented for a pilot-model emplacement system based upon the use of 

 screw piles. 



