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Estimation of spudcan penetration resistance in layered soils from field penetrometer data and quantification of punch-through risk
Punch-through incidents of offshore mobile drilling rig, often occur during preloading, mostly attributable to inadequate site investigation or geotechnical assessment. Combining field data from industry partner and physical modelling, a robust method to evaluate the spudcan performance in multilayer soils directly from penetrometer data is developed. This project concentrates especially on the penetration in carbonate deposit, which is often encountered around Australia.
First, an automated approach for interpretation of soil layering and relevant strength properties from continuous cone penetration data will be developed. Then, by incorporating the existing solutions for single- and two-layer soils, a universal approach to predict the spudcan penetration resistance in multilayer soil profiles will be developed. The resulting penetration resistance profile serves as the basis to assess the potential for punch-through and its likely severity. At last, this procedure is verified through field data and physical centrifuge modelling.
A complete reliance on penetrometer data in evaluating the spudcan penetration will allow an early and accurate planning of damage mitigation response during the jack-up installation. The direct use of the field data also eliminates the uncertainty which often shadows the laboratory test due to the disturbance of samples recovered from the seabed. The result of this research will allow a safer and economic installation of jack-ups in Australian water and support the expansion of offshore exploration industry.