PISA design model for monopiles for offshore wind turbines: application to a marine sand

Abstract

This paper describes a one-dimensional (1D) computational model for the analysis and design of laterally loaded monopile foundations for offshore wind turbine applications. The model represents the monopile as an embedded beam and specially formulated functions, referred to as soil reaction curves, are employed to represent the various components of soil reaction that are assumed to act on the pile. This design model was an outcome of a recently completed joint industry research project – known as PISA – on the development of new procedures for the design of monopile foundations for offshore wind applications. The overall framework of the model, and an application to a stiff glacial clay till soil, is described in a companion paper by Byrne and co-workers; the current paper describes an alternative formulation that has been developed for soil reaction curves that are applicable to monopiles installed at offshore homogeneous sand sites, for drained loading. The 1D model is calibrated using data from a set of three-dimensional finite-element analyses, conducted over a calibration space comprising pile geometries, loading configurations and soil relative densities that span typical design values. The performance of the model is demonstrated by the analysis of example design cases. The current form of the model is applicable to homogeneous soil and monotonic loading, although extensions to soil layering and cyclic loading are possible.

Effect of Stress Level on Response of Model Monopile to Cyclic Lateral Loading in Sand

“…The pile has a closed end, which is appropriate given the wished-in-place installation method. Although full-scale monopiles are open-ended, the contribution of base shear and base moment is typically small (Burd et al 2020). The pile wall thickness is selected to ensure rigid behavior at all three stress levels; such rigid pile behavior is expected to be representative for modern monopiles (e.g., Abadie 2015).…”

Study on Supporting Structure Performance of Deep Soft Soil Foundation Pit near Sea under Waves, Tides, Vibration, and Unbalanced Loads

“…According to the survey report, within the control of the depth of exploration holes, the site rock and soil layers are divided into the Quaternary filling (Q ml ), alluvial soil (Q al ), residual soil (Q el ), and Yanshanian bedrock (r 3 5 ) according to the geological origin. Geological profile around the foundation pit is shown in Figure 4.…”

“…An increasing number of cross-sea tunnels, bridges [1], large-scale wharves, offshore wind turbine structures [2][3][4][5][6], and other major projects have been constructed near seashores, indicating the necessity of more offshore foundation pits. Unlike the traditional foundation pits on land far from the sea [7,8], an offshore foundation pit owns many unique characteristics, such as poor soil quality [9], additional hydraulic loads including waves, tides, and typhoons, and other extreme weather effects.…”

Influence of Pile Diameter and Aspect Ratio on the Lateral Response of Monopiles in Sand with Different Relative Densities

“…The combined load-bearing behavior of large-diameter rigid piles is one of the most crucial factors in the foundation design of OWTs. Among all the On the contrary, the p-y model proposed by Burd et al [25] is part of the output from the most recent research of the PISA project based on the field tests and numerical simulations on large-diameter short monopiles. The model is proposed specifically for the monopile used in offshore wind farms.…”

“…The model is proposed specifically for the monopile used in offshore wind farms. Therefore, before looking into the simulation results from FE modelling, it is worth first discussing and comparing the two p-y models in API [21] and Burd et al [25].…”