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20. Continued 



accurately determined, and that deceleration can be ascertained. The penetrometer 

 reaches a terminal velocity of about 80 feet per second which, based on penetration 

 theory, is sufficient to obtain about 30 feet of penetration in a pelagic clay. It is 

 anticipated that with experience the penetrometer in many cases can be used by itself 

 to design direct-embedment anchorages, thereby eliminating the need for cores and 

 geophysical measurements for this purpose. For other cases, the penetrometer will 

 supplement soil coring and geophysical measurements for anchorage and foundation 

 design. 



Library card 



Civil Engineering Laboratory 



EXPENDABLE DOPPLER PENETROMETER: 



INTERIM REPORT, by R. M. Beard 



TN-1435 21 pp illus April 1976 Unclassified 



1. Doppler Effect Instrumentation I. YF52. 556.999.01.102 



An expendable penetrometer using the Doppler principle has been developed to 

 expediently test seafloor soils at water depths to 20,000 feet. The velocity of the penetrom- 

 eter is measured as it penetrates seafloor soils; from the velocity record, soil penetrability and 

 an estimate of soil strength are available. The penetrometer weighs 365 pounds, is 10 feet long, 

 is 3-1/2 inches in diameter, and is easily deployed from a ship. Initial testing indicates that the 

 I concept of a Doppler instrumentation system is workable, that penetration can be accurately 



determined, and that deceleration can be ascertained. The penetrometer reaches a terminal 

 I velocity of about 80 feet per second which, based on penetration theory, is sufficient to obtain 

 . about 30 feet of penetration in a pelagic clay. It is anticipated that with experience the penetrom- 

 I eter in many cases can be used by itself to design direct-embedment anchorages, thereby eliminating 

 | the need for cores and geophysical measurements for this purpose. For other cases, the 

 ■ penetrometer will supplement soil coring and geophysical measurements for anchorage and 

 foundation design. 



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