shipped in tubes, which experienced less change in sample state 

 (compared to those samples shipped in the corer boxes) . 



A - Parameters. The ratio of the excess pore pressure to the 

 change in principal stress difference, called the A-parameter [42], 

 has been used as a quantitative measure of sample type and sample 

 state change [42]. A-parameters were calculated at the point of 

 maximum principal stress ratio, a /a' max.; values of 0.21, 0.75, 

 and 0.89 were obtained for the three samples, in order of increasing 

 consolidation pressure. Skempton [42] suggests that such values, 

 for clay soils, will result from a lightly overconsolidated clay 

 (Af = 0.21) and from a normally consolidated clay (A = 0.75 and 

 0.89). 



Strength Parameters. The data of Figure 15 have been used 

 to produce the Mohr-Coulomb failure envelope for the calcareous 

 ooze sample, represented, in Figure 16. Here the ordinate represents 

 the shearing stress on a plane and the abscissa represents the 

 normal stress on that plane. Mohr circles at failure are drawn 

 for each sample and enclosed by the assumed failure envelope. In 

 the normally consolidated region, the angle of internal friction, 

 (j) , (from CIU tests) is 0.65 radians (37 degrees). This magnitude 

 appears slightly high when compared to ^ values found for terrestrial 

 clays (Reference 22, p. 443; Reference 38, p. 215) and silts [43] 

 at comparable void ratios, but a (}) = 0.65 radians has been found 

 for other seafloor soils [44, 45, 46]. 



In the overconsolidated portion of the Mohr envelope, the 

 effective cohesion, c, is 3.4 kPa (0.5 psi) and the angle of internal 

 friction, (J), is 0.58 radians (33 degrees) for the assumed straight 

 line fit to the available two data points. 



SUMMARY AND CONCLUSIONS 



A deep-sea calcareous ooze has been subjected to a series 

 of laboratory tests in order to classify the sediment with respect 

 to certain physical properties and engineering index parameters. 

 The engineering properties of the sediment have been defined through 

 one-dimensional compression tests and triaxial shear tests, and 

 observations have been made of sediment grain character changes. 

 The testing and evaluation program, now at an intermediate stage, 

 has developed the following conclusions: 



1. Although the sediment is called a calcareous ooze, and 

 although it is classified as a sandy clay according to the Trilineal 

 Oceanic Soil Classification system [2] , it behaves in an engineering 

 sense as an inorganic silt (Unified Soil Classification System) . 



2. Calcareous ooze samples should be examined and tested on- 

 board ship immediately after acquisition to the fullest extent 



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