Uncertainty-based characterization of piezocone and T-bar data for the Laminaria offshore site

This study provides the results of a reinterpretation of a significant amount of offshore siteinvestigation data within an uncertainty-based framework for the Laminaria site in the Timor Sea between Australia and Indonesia. The general soil profile at the site consists of carbonate soils of silty clay or clayey silt size, extending to a depth of at least 60m below the mudline, with occasional very thin layers of additional silty material. The database comprises seven piezocone and six T-bar penetrometer tests conducted over a 40 sq km region. The spatial variability of seabed soils affects or even governs the failure mechanisms of a foundation. Due to sparse boreholes on an offshore site, the spatial variability in the horizontal direction is often difficult to quantify. This research will take advantage of the piezocone and T-bar penetrometer tests at the Laminaria site to conduct an in-depth study of the horizontal spatial variability. The horizontal spatial variability is first estimated based on piezocone data. This variability will be further reduced by combining with the T-bar penetrometer test data.A kriging method will be introduced to predict borehole data at locations of interest, which results in a large body of data at smaller distances. This technique is shown to greatly enhance the accuracy of the estimation of the horizontal spatial variability. The autocorrelation structure and the horizontal correlation length of the soil strength are obtained for these seabed soils. This study has direct application in the prediction of design values at locations not previously tested.