in unit cone load with depth that probably result from layering. However, 

 the general duplication of test results is quite satisfactory. The results 

 indicate an increasing cone load with depth between about 10 inches and 

 80 inches, and a stiff layer of soil was encountered beyond 80 inches. 

 The vane shear test data are presented (Figure 13) as undisturbed 

 shear strength versus depth to the vane center. Only two sets of tests 

 were performed with the shear vane before mechanical difficulties were 

 encountered with the transducer. A line of best fit is placed between 

 the data points. The data show an approximate linearly increasing shear 

 strength with depth to about 80 inches where a stronger soil layer is 

 again encountered. The presence of the stiff layer reinforces the results 

 of the cone penetrometer tests. 



Site 2 



Soil Properties . Eight short cores were taken within 500 feet of 

 Site 2 by means of a Ewing-type gravity corer. Laboratory analysis of 

 the cores indicates that Site 2 sediment has good areal uniformity. Data 

 from two of the more thoroughly analyzed cores are presented in Figures 

 14 and 15. The grain size distributions are seen to change uniformly 

 with depth. From Tables 6 and 7 the soil classification, according to 

 the Unified Soil Classification System, generally varies from a clayey 

 silt of low plasticity (ML) to a clayey silt of high plasticity (MH) ; 

 however, when classified by the Trilineal System, the sediment varies 

 from a silty sand to a clayey silt (Tables 6 and 7). It should be 

 emphasized that grain size alone (Trilineal System) is not sufficient 

 to specify soil behavior. For engineering purposes, the Unified Soil 

 Classification System presents a more accurate definition of a soil's 

 engineering behavior. 



As at Site 1, the sediment is fairly insensitive (low ratio of 

 undisturbed vane shear strength to remolded vane shear strength) with 

 sensitivities averaging between 1.5 and 2.5. Also, the high liquidity 

 indices (greater than one) indicate a loosely deposited or somewhat 

 unconsolidated sediment in the top three feet of the seafloor. Further 

 analysis showed that the average organic carbon content is 0.5 percent 

 and the average carbonate content is 1.0 percent. 



Laboratory vane shear data taken from the eight Site 2 core samples 

 are plotted on Figure 16. The line of best fit for the average shear 

 strength-depth relationship generally appears to increase uniformly with 

 depth to 3 feet. There is a significant amount of scatter in the data; 

 however, this is attributed primarily to disturbance during core sampling 

 and transporting and soil inhomogeneity. 



In- Situ Test Data . Data from Site 2 are presented in Figures 17 

 through 20. A total of six cone penetrometer tests and six sets of vane 

 shear tests, including both undisturbed and remolded tests, was performed. 



13 



