loss over an extended area. Initially, we only hope to narrow the contributions to 

 this loss by eliminating some secondary effects. Such a great deal of fundamental 

 investigation into the physiochemical and behavior characteristics of the sediment 

 aggregate within small areas of the bottom is required that one is not permitted the 

 license to sample at widely scattered stations over a broad area and interpolate 

 accurately the conditions existing between stations. 



To increase the density of stations sampled per unit time and to eliminate the 

 problems of pressure change caused by elevating bottom samples to the surface, 

 disturbances during sampling, transportation, storage, etc. , as now exists in many 

 coring operations, consideration is being given to the use of in-situ density and 

 water content measuring devices, a field shear strength apparatus, and in-situ 

 acoustic probes. These measurements must be accompanied by core sampling (and 

 laboratory analysis) for comparative purposes for some, as yet, undetermined 

 period. The coring operation will be discontinued when the in-situ measurements 

 are believed to be independently reliable. 



Laboratory analyses and experimentation techniques will continue to provide the 

 basic information concerning geologic-acoustic relationships. Shear strength 

 measurements in the triaxial chamber will be made on all forthcoming core samples. 

 The shear strength parameter may prove to be the most significant single measure- 

 ment required in determining the geologic-acoustic relationships. Since deep ocean 

 sediments possess some rigidity, we can expect some shear wave propagation to 

 take place. Because of the relatively large amplitudes of the shear wave, absorp- 

 tion of this waveform may be a significant parameter to consider in studies of 

 acoustic energy loss. 



In the development of the laboratory analysis program we are working toward 

 the inclusion of an intensive investigation of the dynamic properties of the saturated 

 unconsolidated sediments. The results of a pilot study indicate that the stress- 

 strain relationship for static and dynamic loading of confined or unconfined homo- 

 geneous soil samples is considerably influenced by the void ratio or confining pres- 

 sures. This results in a general trend of increasing modulus with depth. However, 

 variations occur in the vertical sound velocity profile in the non-homogeneous core 

 samples, indicating that other parameters are influencing the sound velocity struc- 

 ture. Therefore, the object of primary concern is to determine the relationships 

 between the gological properties and the elastic moduli. On the basis of the results 

 of the pilot study, it is assunaed that at the low confining pressures (overburden 

 pressures) a Yoimg's modulus can be determined by either a static triaxial or dynamic 

 vibration test. If this assumption is indeed valid, then a transition zone exists in 

 which we hope to develop valid experiments and techniques for dynamic testing of 

 these saturated sediments. 



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