Numerical Modeling of suction caissons in dense sand for general conditions of drainage

Suction caissons have been widely used in the offshore oil and gas industry for over 30 years, but to date have not being extensively used for offshore renewables. They represent a viable solution for the foundations of offshore windfarms, which are gaining momentum as an alternate energy source worldwide. Due to the complex interactions with saturated soils, the behavior of a suction caisson for an offshore wind farm installed in dense sand is currently under vigorous numerical and experimental investigation. This thesis concentrates on using finite element analysis to simulate the behavior of the trailing suction caisson in a multi-bucket jacket in dense sands subjected to monotonic tensile loading. A two-dimensional, axisymmetric hydro-mechanical numerical model is developed to explore the effect of different drainage conditions on the vertical resistance. The suction pressure developed in response to different tensile loading speeds is also examined. For verification of the model, the outputs of the numerical analysis are validated against simple-hand calculations and findings of previous studies. Testing conditions adopted in Centrifuge tests by Senders and Bienne have been recreated for a comparative and parametric study. A complex soil model developed by Whyte is also studied along with Wolfersdorff’s hypoplastic model and the ABAQUS in-built soil model – Mohr Coulomb, in order to determine the most efficient soil failure model to capture the complex undrained behavior of dense sand