The uncertainties associated with the predicted bearing capacity of an offshore gravity platform arise from incomplete knowledge about the type of material that is encountered at different points along the slip surface and the strengths of these materials. Uncertainty about material strength is caused by scatter in test data and differences between measured strength and in situ strength. The probability of finding different materials, given the materials as identified at the location of boreholes, is evaluated from the proximity rule. This is combined with the uncertainty due to data scatter and inaccuracy of the test methods to estimate the variance of the foundation resistance. The procedure makes it possible to evaluate the uncertainty about foundation resistance at various stages of a site exploration program. The effects of additional boreholes and improved testing methods can be evaluated separately and used to help decision making in site exploration. The site exploration data from the Brent B‐G site are analyzed as an example.

Torsional resonant column tests are conducted to study the effect of artificial cementation on low strain dynamic properties of Monterey No. 0 sand. Artificially cemented specimens are prepared using 1, 2, and 4% Portland cement by weight. Specimens were tested after 14 days of curing. It is determined that maximum shear modulus increased and damping ratio decreased with an increase in the degree of cementation. The maximum dynamic shear moduli increased due to corresponding increases in stiffness coefficients. The stiffness ratio defined as the stiffness of cemented to uncemented specimens varied with the degree of cementation and density. Dense specimens rendered higher stiffness ratios. The stiffness ratio was correlated to unconfined compressive strength and the cohesion intercept from CIU tests. Degradation of modulus ratio with strain ratio depended upon both the degree of cementation and density. Decay of modulus was more predominant in stiffer specimens. Cementation led to a decrease in damping ratio at all levels of strain.

Data are presented concerning the shear modulus and damping ratios of sands and gravelly soils as determined by laboratory and field tests. A simple relationship is proposed to relate the shear modulus of a cohesionless soil to a modulus stiffness coefficient, which is a soil property and depends on the characteristics of the soil, and the effective mean principal stress at any point in the soil. Values for the modulus coefficient at low strains are suggested, and it is shown that these values for sands can be estimated from the standard penetration resistance of the sand. Values for gravels are generally greater than those for sands by factors ranging from 1.35–2.5. Suggestions are also made for determining the variation of shear modulus with shear strain and the damping ratios for both sandy and gravelly soils.

A number of currently employed mathematical formulations used in modeling one‐dimensional quiescent consolidation of phosphatic waste clay ponds are reviewed. It is shown theoretically, as well as through an example, that the excess pore water pressure, void ratio, and ground settlements of the models investigated are identical, with the only difference being in the selection of coordinate representation or dependent variables. Correlation between centrifuge prediction of a prototype pond and theory is presented with material parameters obtained from the laboratory. It is concluded that even though the effective stress versus void ratio representation is acceptable, the present laboratory techniques of finding void ratio versus permeability are deficient.