Assessment of grouted connection in monopile wind turbine foundations using combined non-destructive techniques

Research output: Chapter in Book/Report/Conference proceedingConference paper

Abstract

Many large-scale offshore wind farm projects use monopile foundation to obtain a cost effective design. These foundations contain pile-sleeve connections that basically consist of two concentric steel pipes cast together by means of high strength grout. The harsh offshore conditions due to combined action of wind and wave excitations strongly influence the structural integrity as they can lead to potential detachment of the grout. Moreover, at several windfarms, during the construction phase it is noticed that the transition piece (sleeve) is slipping downwards relative to the monopile. This slippage is attributed to a weakening of the adhesion between the grout and the steel causing possible further damage to the grout during extreme operational conditions requiring mitigation to avoid further degradation. In order to eliminate the ambiguities and answer the question as to what extent the damage in the grout is significant for the structural integrity of the monopile, a thorough investigation of grout samples taken from the site is performed. For this purpose, four offshore wind turbines were selected for core sampling. All the samples were subjected to Ultrasonic Pulse Velocity (UPV) Non-Destructive Testing (NDT) and compression testing while a set of samples was also subjected to X-ray analysis. This paper presents the results of the combined use of the X-ray and UPV techniques as well as correlations with compressive strength outputs focusing on the parameters that seem promising for in-situ application.
Original languageEnglish
Title of host publicationEmerging Technologies in Non-Destructive Testing VI - Proceedings of the 6th International Conference on Emerging Technologies in Nondestructive Testing, ETNDT 2016
EditorsDIMITRIOS ANGELIS, Danny Van Hemelrijck, Steve Vanlanduit
PublisherCRC Press
Pages235-239
Number of pages5
ISBN (Print)978-1-138-02884-5
Publication statusPublished - 2016
Event6th International Conference on Emerging Technologies in Nondestructive Testing, ETNDT 2016 - Brussels, Belgium
Duration: 27 May 201529 May 2015

Conference

Conference6th International Conference on Emerging Technologies in Nondestructive Testing, ETNDT 2016
CountryBelgium
CityBrussels
Period27/05/1529/05/15

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