Probabilistic Analysis Of Offshore Site Exploration

Abstract

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 indifferent 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 is 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.