In-Situ Undrained Shear Strength of Two Marine Clays

Field testing was performed at an offshore site approx 2.8 miles (4.5 km) from the New Jersey coast, with water depths of 35 ft ± 5 ft (10.7 ± 1.5 m) to evaluate the undrained strength of two relatively young (8,000 ± yr old) cohesive marine soils; a stiff plastic clay (CH) and a medium-stiff, lean, slightly sensitive clay (CL). Numerous cnsolidation tests indicate that the relatively young Holocene sediments are precompressed resulting in overconsolidation ratios ranging from 3.5 to 6 for the plastic clay (CH) and between 5 and 25 for the silty clay (CL). The normalized undrained shear strength S_u/β_vo from UUC tests and field vane tests were correlated with the overconsolidation ratios of these sediments and compared with the results of K_o-consolidated undrained triaxial compression (CK\a*_o\a*U\a*C), and direct-simple shear (CK\a*_o\a*U\a*DSS) tests.