TY - CONF A1 - Dutto, Paola A1 - Baeßler, Matthias A1 - Geißler, Peter T1 - Suction bucket foundations for wind energy turbines: a numerical study with FEM N2 - Suction Bucket Jackets (SBJ) are found as a suitable alternative to driven piles for the support of jacket or tripod foundations for offshore wind energy converters. Offshore wind energy turbines are characterized by a small self weight and they can be subjected to different load combinations. The work presented here aims to show the numerical investigation on the behavior of suction bucket foundations under different kind of loads as well as load combinations. In order to do so, a suitable numerical model is much needed. The theoretical basis of the model lies on the Swansea formulation of Biots equations of dynamic poroelasticity combined with a constitutive model that reproduces key aspects of cyclic soil behavior in the frame of the theory of generalized plasticity. An adequate FE formulation, the representation of appropriate soil-structure interfaces and the computational efficiency are key aspects in order to successfully model such complex systems. The 3D numerical simulation allows a special insight into the fundamental behavior of the founding of Suction Bucket Jackets such as the evolution of the pore water pressure or the occurrence of the so called soil liquefaction. T2 - OMAE 2016 - 35th ASME International Conference on Ocean, Offshore and Arctic Engineering CY - Busan, South Korea DA - 20.06.2016 KW - Suction bucket jacket KW - Finite Element KW - Offshore geotechnics PY - 2016 SN - 978-0-7918-4992-7 VL - 1 SP - Article UNSP V001T10A004, 1 EP - 8 PB - ASME AN - OPUS4-36688 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Geißler, Peter A1 - Cuéllar, Pablo A1 - Hüsken, Götz A1 - Kühne, Hans-Carsten A1 - Baeßler, Matthias T1 - Insights into compaction grouting for offshore pile foundations N2 - 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. T2 - ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2018) CY - Madrid, Spain DA - 17.06.2018 KW - Offshore Pile Foundation KW - Compaction Grouting KW - Material Point Method KW - Digital Image Correlation PY - 2018 AN - OPUS4-45352 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Geißler, Peter A1 - Schwarz, Johannes A1 - Cuéllar, Pablo A1 - Hüsken, Götz A1 - Baeßler, Matthias A1 - Kühne, Hans-Carsten A1 - Morrone, C. T1 - Compaction grouting to improve the pile bearing capacity in non-cohesive soil N2 - The increasing use of renewable energies leads to a constant search for optimised foundation concepts aiming to reduce the costs for offshore wind turbines. In an ongoing research project, we are developing a design approach for typical offshore driven piles based on the application of injections by compaction grouting directly at the pile shaft. Compaction grouting as a ground improvement technique has been used widely as a countermeasure against liquefaction, settlement and low bearing capacity of soil under new or already existing structures. It is performed by forcing highly viscous grout into the soil to displace and compact the surrounding soil without fracturing or penetrating it. Regarding this injection method, this paper gives a brief overview about general aspects such as appropriate soil characteristics and grouting parameters, grouting equipment and fields of application particularly in the offshore sector. This indicates the ability of our optimisation concept to provide an economic alternative to larger pile dimensions and a retrofitting technique, which is available during the entire lifetime of the foundation and can be deployed only in case of necessity (e.g. excessive deformations or insufficient structural stiffness after an extreme load event). Besides the material feasibility and the constructive realisation of this improvement measure, the development of a corresponding verification concept is crucial in order to ensure the safety and durability of the retrofitted offshore piles. Here we will examine various verification concepts with their respective limitations in the framework of the limit state design. Furthermore, we will present the experimental findings from field tests in sand indicating the advantages of several local injections by compaction grouting for the enhancement of the load bearing behaviour of pile foundations. The test results were also used to validate a numerical model, developed with the finite element program PLAXIS, aiming to predict the expected bearing capacity for different injection scenarios (e.g. grout volume, location of injection points) along a pile shaft. T2 - Twenty-ninth International Ocean and Polar Engineering Conference CY - Honolulu, HI, USA DA - 16.06.2019 KW - Offshore Pile Foundation KW - Compaction Grouting KW - Grout KW - Injection Sequence KW - Tensile Capacity PY - 2019 AN - OPUS4-48504 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Geißler, Peter A1 - Schwarz, Johannes A1 - Cuéllar, Pablo A1 - Hüsken, Götz A1 - Baeßler, Matthias A1 - Kühne, Hans-Carsten A1 - Morrone, C. T1 - Compaction grouting to improve the pile bearing capacity in non-cohesive soil N2 - The aim of an ongoing research project is to develop a design approach for typical offshore driven piles (e.g. Jacket piles) based on the application of injections by compaction grouting directly at the pile shaft. The paper aims to present the results of laboratory and in-situ tests, which reveal the efficiency and the promising potential of the optimised foundation concept for a more economic dimensioning of pile foundations and to increase their bearing capacity in non-cohesive soil at any moment after installation. T2 - Twenty-ninth International Ocean and Polar Engineering Conference CY - Honolulu, HI, USA DA - 16.06.2019 KW - Offshore Pile Foundation KW - Compaction Grouting KW - Grout KW - Injection Sequence KW - Tensile Capacity PY - 2019 SN - 978-1-880653-85-2 SN - 1098-6189 VL - II SP - 2178 EP - 2184 PB - International Society of Offshore and Polar Engineers (ISOPE) CY - Cupertino, California, USA AN - OPUS4-48505 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Geißler, Peter T1 - Verdichtungsinjektionen - numerische und experimentelle Betrachtungen N2 - Die Verdichtungsinjektion stellt ein Verfahren in der Geotechnik dar, bei dem der Baugrund durch Einpressen eines Mörtels mit hoher innerer Reibung verdichtet wird, ohne ihn aufzubrechen. Dieses Verfahren wird weithin verwendet zur Setzungskontrolle oder Erhöhung der Tragfähigkeit des Baugrunds unter neuen bzw. bestehenden Bauwerken. Da die Injektion innerhalb des Bodens stattfindet, ist eine visuelle Beurteilung des Verdichtungserfolgs nicht möglich. Bisher beruht die Beurteilung bzw. Bewertung daher zumeist auf Erfahrungen. Ziel ist es somit mittels numerischer und experimenteller Untersuchungen eine Methode zu erschaffen, die es ermöglicht den Verdichtungserfolg nicht nur vorherzusagen sondern auch bezüglich der Materialparameter des Injektionsguts zu optimieren. Bezüglich der Numerik werden sowohl die grundsätzliche Eignung als auch die ersten notwendigen Anpassungen der impliziten "Material Point Method" zur Simulation einer Verdichtungsinjektion präsentiert. Für die experimentellen Untersuchungen wurde eigens ein Versuchsstand konstruiert, in dem es möglich ist, den Injektionsprozess an einer Glasscheibe zu beobachten und mittels digitaler Bildverarbeitung zu bewerten. T2 - Workshop "Große Verformungen" CY - Berlin, Germany DA - 13.06.2017 KW - Verdichtungsinjektionen KW - Material point method KW - Nichtlinearitäten KW - Updated Lagrange Formulierung KW - u-p-Formulierung KW - Digitale Bildverarbeitung KW - Particle image velocimetry KW - Close range photogrammetry PY - 2017 AN - OPUS4-40894 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Geißler, Peter A1 - Iaconeta, I. A1 - Baeßler, Matthias A1 - Cuéllar, Pablo T1 - Modelling of compaction grouting using the implicit MPM N2 - Compaction grouting involves the injection under high pressure of a highly viscous grout into the soil to displace and compact the surrounding soil without fracturing it. This ground improvement technique has been used widely for settlement control, increasing liquefaction resistance or bearing capacity of soil under new or existing structures. The work presented here aims to show some numerical and experimental investigations being carried out to understand the compaction mechanism and the soil-grout interaction, which is crucial for a successful usage of this technique. To investigate compaction grouting in the laboratory under various stress conditions, a large-scale testing chamber has been developed. The grout was injected directly at the transparent vertical window of the chamber in order to investigate the possibility to monitor the injection process with a camera to measure the in-plane soil displacements and strains by means of the PIV technique. The other aim of this study is to develop a numerical model, which should be able to deal with large displacements and deformations and to simulate the change in shape of the distinct soil-grout interface solely as a result of the interaction between the injected grout and the surrounding soil. Based on these considerations, as a numerical technique, we employ the implicit Material Point Method based on a mixed formulation, which is implemented in the open source Kratos Multiphysics framework. In contrast to standard FE formulations, the usage of the MPM avoids both the numerical instability caused by extensive mesh distortion and the high computational costs of remeshing. The main results focus on the different evolution of the grout bulb inside the soil under various stress states. T2 - 28th ALERT Workshop CY - Aussois, France DA - 02.10.2017 KW - Compaction grouting KW - Soil-grout interface KW - Material point method (MPM) KW - Mixed formulation KW - Particle image velocimetry (PIV) PY - 2017 AN - OPUS4-42432 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Geißler, Peter A1 - Cuéllar, Pablo A1 - Hüsken, Götz A1 - Kühne, Hans-Carsten A1 - Baeßler, Matthias T1 - Insights into compaction grouting for offshore pile foundations N2 - 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. T2 - 37th International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2018) CY - Madrid, Spain DA - 18.06.2018 KW - Offshore pile foundation KW - Compaction grouting KW - Material Point Method (MPM) KW - Mixed formulation KW - Digital Image Correlation (DIC) PY - 2018 SN - 978-0-7918-5130-2 SN - 2153-4772 VL - 9 SP - V009T10A013, 1 EP - 9 AN - OPUS4-46004 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Dutto, Paola A1 - Baeßler, Matthias A1 - Geißler, Peter T1 - Suction buckets behaviour under tensile loads: A numerical study with FEM N2 - Suction Bucket Jackets (SBJ) are found as a suitable alternative to driven piles for the support of foundations for offshore wind energy converters. In the case of jackets or multipods, a predominant vertical load is to be expected. The effect of such a tensile loading is the generation of suction in the soil inside the bucket which leads to an increment of tensile capacity. This paper aims to study the bearing behaviour of a suction foundation by taking into account how the soil permeability and the loading rate influence the foundation behaviour. Moreover, after submitting the structure to a storm load, the bearing capacity is studied again, in order to see the effect of such a load on the bucket's bearing behaviour. This study is carried out by means of Finite Element numerical simulations based on the formulation of Biot's equations combined with a constitutive model that reproduces the key aspects of cyclic soil behaviour in the frame of Generalized Plasticity. T2 - International Ocean and Polar Engineering Conference CY - San Francisco, USA DA - 25/06/2017 KW - Finite element method KW - Offshore wind energy converter KW - Suction bucket KW - Generalized plasticity KW - Sand KW - Numerical simulation KW - Tensile capacity PY - 2017 SN - 978-1-880653-97-5 SP - 485 AN - OPUS4-41051 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -