Monotonic laterally loaded pile testing in a dense marine sand at Dunkirk

Abstract

The results obtained from a field testing campaign on laterally loaded monopiles, conducted at a dense sand site in Dunkirk, northern France are described. These tests formed part of the PISA project on the development of improved design methods for monopile foundations for offshore wind turbines. Results obtained from monotonic loading tests on piles of three different diameters (0·273 m, 0·762 m and 2·0 m) are presented. The piles had length-to-diameter ratios (L/D) of between 3 and 10. The tests consisted principally of the application of monotonic loads, incorporating periods of held constant load to investigate creep effects. The influence of loading rate was also investigated. Data are presented on the overall load–displacement behaviour of each of the test piles. Measured data on bending moments and inclinations induced in the piles are also provided. Inferences are made for the displacements in the embedded length of the piles. These field data will support the development of a new one-dimensional modelling approach for the design of monopile foundations for offshore wind turbines. They also form a unique database of field measurements in a dense sand, from lateral loading of piles at a vertical distance above the ground surface.

Using FBGS to estimate the horizontal response of a monopile in a geotechnical centrifuge

“…In the literature, three experimental methods exist to characterise the response of pile or monopile under transversal loads: i) the full-scale field tests (e.g. Davisson and Salley, 1969;Baguelin et Jézéquel, 1972Reese et al, 1974;Ting, 1987;Little and Briaud, 1988;Koukoura et al, 2015;Barbosa et al, 2017;Jardine et al, 2018;McAdam et al, 2018); ii) reduced-scale laboratory tests (e.g. LeBlanc et al, 2010;Abadie et al, 2018) and iii) reduced-scale centrifuge tests (e.g.…”

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

“…The OWTs are subjected to combined horizontal force and overturning moment simultaneously from the actions of wind, wave and currents. The equivalent loading eccentricity of horizontal force can reach 2.5L (L is pile embedded length) above the ground surface [9,10]. The combined load-bearing behavior of large-diameter rigid piles is one of the most crucial factors in the foundation design of OWTs.…”

“…Instead of soil friction angle, the model parameters of the PISA p-y model are defined in terms of soil relative density. It should be noted that the model parameters in Table 1 were proposed based on the numerical simulations validated against the field tests performed in a dense marine sand at Dunkirk [10].…”

Optimization of Impact Pile Driving Using Optical Fiber Bragg-Grating Measurements

“…Fiber Bragg-grating (FBG) sensors have been used previously to measure distributed strain during pile load testing on, e.g., largediameter concrete piles (Schmidt-Hattenberger et al 2003), bored piles (Lee et al 2004), and jacked piles (Liu and Zhang 2012). The robust application of FBG sensors on impact-driven steel piles was demonstrated by Doherty et al (2015) and the technology was used to measure soil-structure interaction during lateral load pile testing for the Pile Soil Analysis (PISA) project (Byrne et al 2019;McAdam et al 2019). The latter authors monitored the FBG sensors during pile driving at a rate of 1 kHz that, while relatively fast, could not provide high-resolution records of the traveling stress waves.…”