Numerical Analysis of Large-Diameter Monopiles in Dense Sand Supporting Offshore Wind Turbines

Abstract

Large-diameter monopiles are widely used foundations for offshore wind turbines. In the present study, three-dimensional finite-element (FE) analyses are performed to estimate the static lateral load-carrying capacity of monopiles in dense sand subjected to eccentric loading. A modified Mohr–Coulomb (MMC) model that considers prepeak hardening, postpeak softening, and the effects of mean effective stress and relative density on stress–strain behavior of dense sand is adopted in the FE analysis. FE analyses are also performed with the Mohr–Coulomb (MC) model. The load–displacement behavior observed in model tests can be simulated better with the MMC model than with the MC model. On the basis of a parametric study for different length-to-diameter ratios of the pile, load–moment capacity interaction diagrams were developed for different degrees of rotation. A simplified model, based on the concept of lateral pressure distribution on the pile, is also proposed for the estimation of its capacity.