During the test program, nine different bearing plates (0.5, 0.75, 1 .0, 

 1 .25, and 1 .5 feet in diameter and 0.5, 0.75, 1 .0 and 1 .25 feet square) were 

 used to investigate the effect of plate size and shape on the resulting bearing 

 pressure— settlement response. The plates are made of one-half-inch steel 

 plate, having a smooth painted surface, and are stiffened with steel webs to 

 provide rigidity. The connection between the plates and the device is also 

 rigid in order to keep the plate in the horizontal plane. 



The displacement rate at which most of the tests were performed did 

 not vary a large amount. The slowest test had a displacement rate of 0.0142 

 in. /sec, and the fastest test was run at 0.0663 in. /sec, which is about 5 times 

 as fast as the slowest test. For the tests actually analyzed in this report, the 

 displacement rate varied by a factor of about 2.5. Most of the tests were run 

 at about 0.03 to 0.04 in. /sec resulting in a test time of about 5 minutes for 

 11 inches of displacement. 



RESULTS OF TESTS 

 Soil Properties 



Three sediment cores at the Series 1 1 1 test site and two cores at the 

 Series IV site were obtained using an Ewing-type gravity corer with a plastic 

 liner and a "modified hinged" core retainer. The lateral distances between 

 the cores at each site were less than a few hundred feet. 



The results of laboratory analyses of the cores, including grain size, 

 original water content, bulk wet density, Atterburg limits, and original and 

 remolded vane shear strengths, are presented in Figures 4 through 8. According 

 to the Trilineal Oceanic Soil Classification Chart, ^ the sediment throughout the 

 lengths of the cores from Site 1 1 1 is classified as a clayey silt. The sediment at 

 Site IV is a silty clay. The results of laboratory tests performed on cores from 

 the same site do not vary greatly, evidently indicating that the soils at both 

 sites have fairly good areal uniformity for the small areas represented by the 

 cores. 



All of the vane shearing strength data for the Series II I and Series IV 

 sites is presented in Figures 9 and 10. Both sets of data indicate an essentially 

 linear increase in shear strength with depth. The strength at the surface for 

 the Series 1 1 1 data is practically zero while the surface strength for the Series 

 IV data is somewhat greater than zero. 



The linearly increasing strength profiles may be attributable to either 

 consolidation under the weight of overlying sediment or the effects of increasing 

 age with depth or a combination of the two effects. The finite surface strength 

 at Site IV may be due to either the removal of several inches of sediment by 

 scour, the effect of age, or the existence of an intrinsic strength which is pro- 

 duced as soil particles come together in a flocculating environment. 



