The overall packaging of the accelerometer and corer/penetrometer 

 was developed by W. L. Preslan of the University of Delaware. Figure 2 

 shows the overall configuration of the device which included a lifting 

 eye, weights, a case for the accelerometer, a "quick change" mechanism 

 for accommodating either the corer or penetrometer, and, in this 

 particular photograph, the penetrometer. The dimension from the top 

 of the eye to the bottom of the accelerometer case is 62 inches. The 

 accelerometer case is 7 inches in outside diameter and the weights are 

 15 inches in outside diameter. The penetrometer is an inverted cone 

 with a base of 2 inches and a height of 2 inches and is attached to a 

 74-inch-long , 1-inch-O.D. shaft. The corer is a 69-inch-long tube 

 with a 3.25-inch-O.D. and a 3.00-inch-I.D. The mass of the corer 

 and penetrometer is approximately 5.4 slugs. 



TESTING PROGRAM 



During December 1969, NCEL performed two series of coring and 

 penetration tests. The two test sites were at depths of approximately 

 120 feet (Pitas Point Site) and 1200 feet (1200-Foot Site), (see 

 Table 1) . The corer/penetrating device was connected to a lowering 

 line by a triggering mechanism of the type usually used in oceanographic 

 coring. The triggering mechanism was activated by a 20-foot line 

 extending below it. The device was lowered to within 20 feet of the 

 bottom by the ship's winch, where the triggering mechanism was 

 activated, thus allowing the corer/penetrometer to free-fall into the 

 seafloor. The tests also included a timing mechanism because of the 

 limited recording capacity of the accelerometer. The commencement 

 of recording had to be delayed, by this timer, at the 1200-Foot Site 

 to ensure that the final portion of the test would be recorded. 



SOIL TESTS 



A series of standard soil index property tests was performed 

 on the soil samples obtained at each site for soil classification 

 purposes and for possible usage in future penetration test 

 correlations. These results are summarized in Tables 2 through 7. 

 In addition, a series of vane shear tests planned so as to indicate 

 soil viscous effects was performed on the samples obtained. The 

 speed of vane rotation was varied among four different rates from 

 test to test. Plots of undisturbed and remolded strength versus depth 

 for two rotation rates at each site are included in Figures 3 through 

 6. The order of testing was randomized so as to eliminate any overall 

 differences between cores. 



As may be seen there is a distinct rate effect for all cases. 

 It is a stronger effect with undisturbed soil than with remolded soil, 

 and it does not appear to increase significantly with soil strength. 



