Accounting for the spatial variability of soil properties in the reliability-based design of offshore piles

摘要

The inherent spatial variability of a mechanical soil property can be an important source of uncertainty. The uncertainty in soil properties affects the design of geotechnical structures, such as offshore piled jackets. The complete geostatistical characterization of a soil property requires that the mean, variance and the scale of fluctuation of the property be obtained. From the results of piezocone penetration tests (CPTU) at the location of one piled jacket offshore, the vertical scale of fluctuation of the cone resistance at different depths was determined using random field theory. The effect of accounting for spatial averaging on the reliability-based design of the axial capacity of piles is illustrated through a reliability analysis of axial pile capacity with calculation of annual probability of failure. The results show that offshore clays and sands can exhibit significant inherent spatial variability. Accounting for spatial averaging in the vertical direction can influence the results of reliability-based design of offshore piles, and can potentially lead to a more optimal and cost-effective pile penetration depth.