NAVAL IN-PLACE SEAFLOOR SOIL TEST EQUIPMENT: A PERFORMANCE 

 EVALUATION 



Technical Note N-1135 



YF 38.535.002.01.001 



by 



R. J. Taylor and K. R. Demars 



ABSTRACT 



The Naval Civil Engineering Laboratory (NCEL) has developed a 

 vane shear and cone penetrometer apparatus capable of obtaining the 

 in-place undrained shear strength of sediments to a depth of 10 feet 

 in the seafloor. The device is a subsystem of the Deep Ocean Test 

 In-Place and Observation System (DOTIPOS) . Information obtained with 

 this equipment will enhance the Navy's ability to design foundations 

 more economically and reliably for seafloor installations. The results 

 of tests performed at 100- and 600-foot deep sites and the evaluation 

 of DOTIPOS and the vane shear and cone penetrometer apparatus are 

 presented. 



The DOTIPOS-mounted vane shear and cone penetrometer apparatus 

 operates satisfactorily to water depths of 600 feet and produces 

 results which appear reasonable when compared to previous theoretical 

 and laboratory experimental results. Laboratory and in-situ vane 

 shear results are in reasonable agreement; however, the in-sltu results 

 exceed the laboratory results by 10 to 20 percent. A relationship 

 between percent clay content of the sediment and the ratio of cone 

 resistance to vane shear strength appears feasible for seafloor sediments, 

 Verification of this relationship will establish the cone penetrometer 

 as a more useful and economical site survey tool. 



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