Seafloor penetration in general was discussed in some detail 

 in two state-of-the-art contract reports funded by NCEL. In one of 

 these reports, 5 authored by Dr. W. E. Schmid of Princeton University, 

 the existing techniques for analyzing and predicting object penetration 

 are presented and discussed. It is concluded that much of the past 

 research involving high speed ballistic penetration of soil and other 

 materials is not directly applicable to seafloor penetration. The 

 equations which have been developed are empirical and contain 

 coefficients which reflect the characteristics of high speed 

 penetration but do not consider the unique properties of soft seafloor 

 soils. The limited work which is applicable to seafloor penetration 

 is considered next, and several closed-form equations for the 

 penetration of idealized objects (primarily spheres) into homogeneous 

 materials with combined velocity-dependent and static properties 

 are developed. It is concluded that velocity dependent terms should 

 be included in penetration prediction and that additional research 

 is required to determine the characteristics of these terms. Some 

 data for the low speed penetration of terrestrial soils are given, 

 but virtually no data for seafloor penetration are provided. 



In the other state-of-the-art report, ° authored by Dr. R. J. Smith 

 of the Naval Postgraduate School, a brief review of past penetration 

 research is also included. Most of the report is concerned with a 

 statement of the technique currently used by the Navy to predict 

 object penetration. This technique involves a step-by-step 

 numerical solution based on work-energy concepts. Forces acting 

 upon an object during penetration are calculated using classical 

 static soil mechanics equations evaluated in terms of static soil 

 properties. No data are included to verify the technique. 



As a result of this previous work and the subsequent conclusion 

 that seafloor penetration is not currently well understood, NCEL, 

 under the sponsorship of the Naval Facilities Engineering Command, 

 initiated in 1969 a study of the physical processes involved. The 

 objective of this study is to develop capabilities to predict the 

 penetration behavior of any object given object configuration, soil 

 properties and boundary conditions. 



This report considers an initial phase of the study, a limited 

 series of in situ penetration tests which were conducted during 

 December 1969. Free-fall penetration was selected for investigation 

 in these tests because it is a form which is relatively easy to 

 analyze, existing equipment could be used, and the results could 

 be applied toward a number of seafloor engineering problems. 



OBJECTIVES 



The objectives of this report are (1) to present the results of a 

 series of in situ penetration tests, (2) illustrate the capabilities 

 of existing penetration evaluation equipment, (3) discuss the value 



