strength profile and the location of layer interfaces should be detectable. 

 Acoustic techniques can also detect layering if the soil density increases 

 significantly from layer to layer with increasing depth. However, 

 acoustics cannot detect layers if the soil density decreases with depth. 

 The penetrometer will be of value in determining the occurrence of 

 anomalous conditions. At selected anchorage sites multiple penetrometer 

 tests will help assess the probability of occurrence of small submarine 

 lava flows and ice-rafted detritus. The extent of ''pavement'' formations, 

 extremely soft sediments, and layered sediments can also be determined 

 with multiple penetrometer tests. Lava flows and detritus will be 

 apparent from a lack of penetration (surface formation) or abruptly 

 interrupted penetration (subsurface formation) . The other conditions 

 will require interpretation of the data record, but the records are 

 expected to be quite different from those of normal soil formations. 



PENETROMETER DESIGN 

 Vehicle Development 



The shape and weight of the vehicle were to allow penetration of 

 30+ feet into typical deep ocean clay soil deposits and yet were to 

 maintain low cost. Lowest cost for the vehicle was considered to be 

 synonomous with minimum size, simple shape, and ease of fabrication. 

 The design process involved a parametric study with a wide range of 

 sizes of solid steel and lead-filled pipe vehicles. Performing the 

 parametric study required determining penetration and terminal velocity 

 of each shape considered. 



Penetrations were calculated using a simplified form of that presented 

 by Migliore and Lee (1971). In this method the initial kinetic energy 

 of the penetrating object is depleted by the work done as the object 

 penetrates into the seafloor. Calculations were performed on an incremen- 

 tal basis. That is, work done over short distances was subtracted from 

 the kinetic energy of the penetrator until its kinetic energy was 

 dissipated. Mathematically, 



AKE = I N A.c + A cl Ad (2) 



I c f s I 



where AKE = work done 



N = bearing capacity factor (10) 



A = frontal area of object 



c = soil cohesion 



A = side area of object 

 s 



A = depth increment 



