INTRODUCTION 



Object penetration into the seafloor is an important mechanism 

 occurring in many Naval undersea operations. For example, whenever 

 a seafloor structure is placed, the foundation will penetrate the 

 seafloor to some extent. In some instances, including pile and 

 embedment anchor installation, it will be desirable to obtain large 

 penetration, while in other instances, including spread footing 

 placement, it will generally be desirable to minimize penetration 

 behavior of the foundation. 



Other situations in which seafloor penetration plays a major 

 role are search and salvage operations involving missing or sunken 

 ships and ordnance. When Naval equipment is lost and presumed to 

 be embedded in the seafloor, it is of value to be able to predict 

 possible ranges of embedment depths so that the nature of the search 

 mission can be planned accordingly. 



Another important application of seafloor penetration involves 

 the use of penetrators, dynamic or static, to measure soil engineering 

 properties. Such devices as these might eventually become among 

 the most economical tools for obtaining large quantities of soil 

 information for use in site selection or the design of small 

 foundations. However, the mechanism of seafloor penetration must 

 be better understood before such pieces of testing equipment can 

 be used effectively. 



On the basis of these applications, several research projects 

 have been sponsored by the Navy to develop better techniques for 

 predicting and utilizing seafloor penetration. 



BACKGROUND 



The Naval Civil Engineering Laboratory (NCEL) has pursued 

 several projects related to the penetration problem. In early efforts, 

 the major emphasis was directed toward static penetration. A seafloor 

 plate bearing device and a static cone penetrometer were developed 

 and tested at various seafloor locations off the coast of California. 

 The results of these tests were analyzed and techniques for using 

 the results were developed and presented in technical reports. ' 



Vibratory and explosive embedment anchors which utilize the 

 penetration mechanism as means of installation have also been developed 

 by NCEL.3>^ Some penetration data have been acquired with these devices 

 and analyzed, but the full potential of this equipment as a means for 

 investigating penetration has not as yet been realized. 



