Site investigations were recently performed offshore at three prospective plat-form sites in water depths between 400 and 500 m in the Gulf of Mexico. Soil conditions at the sites generally range from very soft clays near the seafloor to very stiff clays at 120- to 150-m penetration. Analyses of stress history indicate the soils at these locations are generally normally consolidated. Laboratory tests were performed on recovered specimens to deter-mine the undrained shear strength. Standard laboratory miniature vane shear tests and unconsolidated-undrained triaxial tests were performed in addition to consolidated-undrained tests using stress history and normalized soil engineering properties (SHANSEP) procedures. Tests performed in the field included in-situ vane and cone penetrometer. Cone factors Nk were computed using in-situ vane shear strengths as the reference strength. This paper compares the results of consolidated-undrained (SHANSEP) laboratory and in-situ tests to determine a relationship that may be used to correlate these results. The effects of soil strength and plasticity are examined and used to correlate shear strength with the liquidity index. A comparison is also made between peak and residual in-situ vane strengths. This paper further describes how a combination of these in-situ and laboratory tests can be used to characterize a deepwater site for foundation design. Recommendations for future site investigations are also discussed.

Description Cyclic and dynamic testing of soils for geotechnical engineering purposes and centrifuge testing has emerged as a new tool for understanding soil behavior and dynamic soil-structure interaction. STP 1213 is an excellent reference document on these latest testing practices, and emerging technologies and provides additional information on measuring soil properties used cyclic and dynamic loading conditions. 25 peer-reviewed papers give you an understanding of field, laboratory, and centrifuge methods used in cyclic and dynamic testing of soils for geotechnical engineering purposes. The papers discuss: • Descriptions of facilities, apparatus, and instrumentation used • Theoretical analysis of apparatus and/or instrumentation • Results and analysis of experimental research • Discussion of testing procedures, improvements, and guidelines