Ultimate Load Capacity of Caisson Foundations and Anchors in Sand
Abstract
Caisson foundation is a promising alternative and a primary anchoring candidate for offshore floating wind turbine. Although suction caisson is a common foundation solution that has been used in the oil and gas industry, its application in offshore floating wind turbine differs significantly in terms of the anchor aspect ratio, load magnitude, and soil type.
Most of the practical experience from the oil and gas industry and studies in the literature have largely focused on caissons capacity in cohesive soils.
In this study, a three-dimensional finite element model is developed to estimate the capacity of caisson anchors in sand where the drained condition is of prime importance. After the model is validated by comparing its results to measured data from centrifuge tests, the model then is utilized in the scope of a parametric study to investigate the effect of load attachment depth (Li), Load inclination angle (θ), aspect ratio and soil relative density (Dr). Mohr-coulomb constitutive model has been the primary model that is used to model the soil in this study and two of its parameters friction angle (ф) and dilation angle(ψ) have been assessed to evaluate their effect on the ultimate capacity and failure behavior.
A simplified method using an upper bound formulation of plasticity limit analysis is proposed to estimate the lateral load capacity of suction anchor in sand. The plastic limit analysis model offers a quick estimate of lateral load capacity for the caisson anchor, and it provides an uncomplicated way to assess the effect of key parameters on the caisson anchor capacity. In addition to the main project, two projects are considered in this study. First project is the lateral capacity of multiline ring anchor in sand. The second project is bucket foundation under high moment demands for fixed foundation offshore wind towers.
Subject
Finite element analysisPlastic limit analysis
Offshore wind turbines
Anchor capacity
sand
Multiline ring anchor
Bucket foundation
inclined loading
Citation
Aldawwas, Anas Suliman M (2022). Ultimate Load Capacity of Caisson Foundations and Anchors in Sand. Doctoral dissertation, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /197380.