The samples were treated in different ways so that various effects 

 of disturbance could be analyzed. The types of treatment were as follows: 



Standard . Samples were stored under refrigerated, 100 percent 

 humidity conditions and tested as soon as possible. Vibrations and 

 other forms of mechanical disturbance were minimized. It was originally 

 intended to store these samples vertically, as has been the standard 

 practice in oceanographic work. However, after a few weeks, it became 

 apparent that vertical storage was leading to partial consolidation. 

 All samples were then laid horizontally for the remainder of the program. 



Nonref rigerated Storage . Samples were maintained at approximately 

 75°F during the period before testing ( 1 to 6 months) , but otherwise 

 treated as "standard." 



High-Frequency Vibration . Samples were vibrated for 30 minutes at 

 40 KHz in an ultrasonic cleaner before testing, but otherwise treated 

 as "standard." 



Low- Frequency Vibration . Samples were vibrated for 60 minutes at 

 27 Hz on a sieve shaker before testing, but otherwise treated as 

 "standard. " 



Long-Term Storage . Samples were stored for slightly over one year 

 before testing, but were otherwise treated as "standard." 



Very Long Term Storage . A set of samples is being retained for 

 testing after two or three years to determine the influence of very long 

 storage. Results of this extended storage will be presented in a later 

 report. 



An experimental design was developed so that the influence of each 

 of the deviations from standard could be determined for each of the 

 test sites and for each sediment depth range. The test plan and labora- 

 tory test results (initial and remolded vane shear, residual negative 

 pore water pressure, and water content) are listed in Tables III, IV, 

 and V. The tests, with the exception of those subjected to long-term 

 storage, were performed in a random order. 



About 50 triaxial tests (consolidated and unconsolidated-undrained 

 with pore pressure measurements) were performed on samples taken from 

 these cores. The complete results and a description of the testing 

 techniques will be presented in a later report on the shear strength of 

 cohesive seafloor soils. 



In addition, a supplementary study of the characteristics of in- 

 situ shear stress removal ("perfect sampling") was undertaken using 

 samples from the 100-foot site. It was found that in-situ shear stress 

 removal alone could account for as much as a 15 percent reduction in 

 strength when dealing with a silty material like that at the 100-foot 



11 



