Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-46004 Beitrag zu einem Tagungsband Geißler, Peter; Cuéllar, Pablo; Hüsken, Götz; Kühne, Hans-Carsten; Baeßler, Matthias Insights into compaction grouting for offshore pile foundations The authors are currently investigating the possibility to apply compaction grouting for offshore pile foundations (Jacket piles as well as monopiles) as a possible retrofitting technique for an optimised foundation concept. In this research project, we are developing a design approach aiming to predict the ideal amount and properties of a grout for a specific soil situation and desired improvement of pile bearing capacity after Installation and during service time. Both numerical and experimental tests have been carried out to investigate the injection process during which a highly viscous grout is injected into the soil under high pressure to displace and compact the surrounding soil without fracturing it. The implicit Material Point Method (MPM) based on a mixed formulation is the numerical technique chosen to deal with the expected large deformations and the arbitrary shape of the developing grout bulb. The usage of MPM prevents both the need of remeshing and the numerical instability induced by extensive mesh distortion. For validation with experimental results, we have constructed a testing chamber with one transparent sidewall. This chamber enables us to observe the injection process directly at the transparent vertical window and to measure the in-plane soil displacements and strains by means of the Digital Image Correlation (DIC) technique. The results already reveal the interrelation of soil and grout properties for a successful usage of this common ground improvement technique. 2018 Proceedings of the ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering OMAE 2018 9 978-0-7918-5130-2 37th International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2018) Madrid, Spain 18.06.2018 22.06.2018 V009T10A013, 1 9 2018-09-21 OPUS4-48444 Beitrag zu einem Tagungsband Kullolli, Borana; Baeßler, Matthias; Cuéllar, Pablo; Rica, S.; Rackwitz, F. An enhanced interface model for friction fatigue problems of axially loaded piles The shaft bearing capacity often plays a dominant role for the overall structural behaviour of axially loaded piles in offshore deep foundations. Under cyclic loading, a narrow zone of soil at the pile-soil interface is subject to cyclic shearing solicitations. Thereby, the soil may densify and lead to a decrease of confining stress around the pile due to microphenomena such as particle crushing, migration and rearrangement. This reduction of radial stress has a direct impact on the shaft capacity, potentially leading in extreme cases to pile failure. An adequate interface model is needed in order to model this behaviour numerically. Different authors have proposed models that take typical Interface phenomena in account such as densification, grain breakage, normal pressure effect and roughness. However, as the models become more complex, a great number of material parameters need to be defined and calibrated. This paper proposes the adoption and transformation of an existing soil bulk model (Pastor- Zienkiewicz) into an interface model. To calibrate the new interface model, the results of an experimental campaign with the ring shear device under cyclic loading conditions are here presented. The constitutive model shows a good capability to reproduce typical features of sand behaviour such as cyclic compaction and dilatancy, which in saturated partially-drained conditions may lead to liquefaction and cyclic mobility phenomena. Glasgow, Scotland ASME 2019 OMAE 2019 2019 Conference: OMAE Glasgow, Scotland, UK 09.06.2019 14.06.2019 Article Number: UNSP V001T10A013 2019-07-15