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 - Cuéllar, Pablo T1 - Deep foundations for offshore wind turbines T1 - Cimentaciones profundas para aerogeneradores marinos N2 - This presentation deals with the phenomenology and design of pile foundations for offshore wind turbines, and is divided in two lectures. The first lecture presents a brief introduction to the context and peculiarities of such foundations, and then focuses on the particular case of axially loaded piles. This part is most relevant for the relatively slender piles of the multi-pile substructures (i.e. jackets and tripods). A clear distinction between physical phenomenology and practical design is drawn here. The second lecture continues with the case of lateraly loaded offshore piles, which bears most relevance for the case of the monopile foundations. Here again, a clear separation between physical reality and design methods is intended. Finally, the last part of the second lecture introduces several advanced topics which lie outside the classical design approaches, namely the cyclic pile fatigue and the so-called pile setup (i.e. the time effects on the axial pile capacity). The relevance of these two topics is illustrated with experimental results from a field testing campaign on real large-scale piles. T2 - Masters course on Soil Mechanics and Geotechnical Engineering. Geotechnical Laboratory of CEDEX CY - Madrid, Spain DA - 13.04.2018 KW - Offshore pile foundations KW - Load bearing behaviour KW - Design methods PY - 2018 AN - OPUS4-46311 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Baeßler, Matthias A1 - Cuéllar, Pablo A1 - Victor, A. A1 - Lüddecke, F. ED - Triantafyllidis, T. T1 - Stability and large deformations of slender structures supported by soil materials N2 - The stability and geometric nonlinearities of slender structures are a major topic in structural design. While this topic is most relevant in the field of Structural Engineering, e.g. for steel or concrete structures, only few applications take the role of soil-structure-interaction explicitly into account. The focus of this paper is placed on the impact of soil support and its modelling for the buckling analysis based on examples both for pile foundations and for railway track stability. The general interaction between steel design and the geotechnical input will be addressed. The paper discusses and summarizes a range of subtopics based on experience and current research at the author’s institute. KW - Buckling soil-structure-interaction offshore piles track PY - 2020 SN - 978-3-030-28515-9 SN - 978-3-030-28516-6 DO - https://doi.org/10.1007/978-3-030-28516-6 SN - 1613-7736 SN - 1860-0816 VL - 91 SP - 355 EP - 369 PB - Springer CY - Cham, Switzerland AN - OPUS4-49166 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo T1 - Mechanical design challenges for offshore wind-farms N2 - This talk provides a brief introduction on general engineering aspects of offshore wind energy production. Some geomechanical issues for the foundation of OWTs into the seabed are introduced, while the results from experimental investigations and coupled computational analysis are discussed. In the second part of the seminar, the hydromechanical Wave–Tower interaction is firstly discussed. Then, some general aspects of the windfarm aerodynamics are introduced. On the one hand, some modelling possibilities for the wake analysis of single turbines and turbine groups are discussed. And on the other hand the relevance of such analyses for a proper windfarm layout optimization is pointed out. Concerning the geomechanical issues the talk shows that: i) The pile’s bearing capacity can degrade under cyclic loading (waves, wind, …). ii) The time effects can be relevant: Capacity improvement can be substantial, but also fragile. iii) There are cyclic PWP effects: Cyclic interaction with pore water may lead to soil softening and an uncoupled analysis (current design practice) is potentially unsafe. And concerning the hydromechanical and aerodynamical design considerations, this seminar shows that: i) Numerical analysis of turbine’s interaction with wind/waves is useful and affordable. ii) Simplified models can provide insight into windfarm aerodynamics. iii) Turbulent wake analysis is very relevant for the windfarm layout. T2 - Energy Science Kolloquium, Fakultät für Physik, Universität Duisburg-Essen CY - Duisburg, Germany DA - 11.10.2018 KW - Geomechanics of offshore foundations KW - Wave-Tower interaction KW - Windfarm wake analysis PY - 2018 AN - OPUS4-46313 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kemmler, Samuel A1 - Cuéllar, Pablo A1 - Rettinger, C. A1 - Köstler, H. T1 - A Fluid-Solid Coupled Micromechanical Simulation for the Analysis of Piping Erosion During the Seabed Installation of a Suction Bucket Foundation N2 - Suction buckets are a promising concept for the foundations of offshore wind turbines. During the installation process of a suction bucket, localized fluidization of the granular soil, so-called piping erosion, may lead to installation failure. A 3D fluid-solid coupled micromechanical simulation is presented to study the occurrence of piping. An Euler-Lagrangian coupling employs momentum exchange between the fluid phase and the geometrically resolved particles. We investigate the behavior of the soil for three cases with varying prescribed suction velocities. We observe piping in the case with the highest suction velocity by analyzing the deformation of the granular fabric and monitoring the differential pressure. The grains under the bucket wall-tip show the highest hydraulic gradients and forces at the onset of piping. This approach permits a detailed analysis of piping phenomena and brings novel insights on the triggering conditions for piping failure of suction-aided foundations. T2 - TC 105 International Symposium CY - Grenoble, France DA - 23.09.2024 KW - Micromechanical simulation KW - Piping erosion KW - Suction bucket foundation PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-629461 DO - https://doi.org/10.1088/1755-1315/1480/1/012024 SN - 1755-1307 VL - 1480 IS - 1 SP - 1 EP - 4 PB - IOP Publishing AN - OPUS4-62946 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kemmler, Samuel A1 - Cuéllar, Pablo A1 - Artinov, Antoni A1 - Luu, Li-Hua A1 - Farhat, Abbas A1 - Philippe, Pierre A1 - Rettinger, Christoph A1 - Köstler, Harald T1 - A fully-resolved micromechanical simulation of piping erosion during a suction bucket installation N2 - Granular fluidization phenomena such as piping erosion represent a challenge to the delicate installation process of offshore suction bucket foundations. A detailed analysis of the complex conditions in terms of soil composition, soil state, and foundation installation parameters that may lead to piping can be very demanding, if at all possible, solely by experimental means or using macroscopic continuum-based seabed models. The present paper presents a fully-resolved fluid-coupled micromechanical approach for a three-dimensional numerical simulation of the installation process of a suction bucket using the lattice Boltzmann method and discrete element method. The developed model is validated using well-established benchmarks and calibrated by means of experimental data from physical model tests on relevant scenarios focusing on the local fluidization of fixed embedded suction buckets as well as on the suction-driven installation of unrestrained buckets. The qualitative and quantitative agreement with the experimental data both endorse the proposed methodology and highlight the physical soundness of the obtained results. Thereby, the paper shows that three-dimensional analyses of relevant local scenarios at a real scale with little macromechanical model assumptions are feasible. KW - Micromechanical simulation KW - Fluid–solid coupling KW - Piping erosion KW - Suction bucket foundation KW - Offshore wind support structure KW - High-performance computing PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-633790 DO - https://doi.org/10.1016/j.compgeo.2025.107375 SN - 0266-352X VL - 186 SP - 1 EP - 17 PB - Elsevier B.V. AN - OPUS4-63379 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Baeßler, Matthias A1 - Cuéllar, Pablo A1 - Schepers, Winfried T1 - VERBATIM: Project Introduction and Large Scale Experiments N2 - The presentation summarizes the scope of the joint project VERBATIM on buckling of large Monopiles. The presented work from the authors focusses on the experimental field tests of large predented piles during driving and a numerical investigation on the observed buckling behaviour. T2 - Colloquium „Buckling of Offshore Wind Energy Structures“ CY - Berlin, Germany DA - 14.02.2024 KW - Buckling KW - Offshore KW - Wind Energy Structures KW - Monopiles KW - Pile-Tip-Buckling PY - 2024 AN - OPUS4-59535 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zinas, Orestis A1 - Papaioannou, Iason A1 - Schneider, Ronald A1 - Cuéllar, Pablo T1 - Multivariate Gaussian Process for 3D subsurface stratigraphy prediction from CPT and labelled borehole data N2 - Quantifying uncertainties in subsurface properties and stratigraphy can lead to better understanding of the ground conditions and enhance the design and assessment of geotechnical structures. Several studies have utilized Cone Penetration Test (CPT) data and employed Bayesian and Machine Learning methods to quantify the geological uncertainty, based on the Robertson’s soil classification charts and the Soil Behaviour Type Index (Ic). The incorporation of borehole data can reduce the stratigraphic uncertainty. Significant challenges can arise, however, mainly due to the intrinsic differences between field and laboratory-based soil classification systems, which can potentially lead to inconsistent soil classification. To this end, this study proposes a multivariate Gaussian Process model that utilizes site-specific data and: i) jointly models multiple categorical (USCS labels) and continuous (Ic) variables, ii) learns a (shared) spatial correlation structure and the betweenoutputs covariance, and iii) produces two types of dependent classification outputs. The results indicate that the integration of geotechnical and geological information into a unified model can provide more reliable predictions of the subsurface stratification, by allowing simultaneous interpretation of USCS and Ic profiles. Importantly, the model demonstrates the potential to integrate multiple variables of different types, aiming to contribute to the development of a methodology for joint modeling of geotechnical, geological and geophysical data. T2 - 7th International Conference on Geotechnical and Geophysical Site Characterization CY - Barcelona, Spain DA - 18.06.2024 KW - Geotechnical site-characterization KW - Probabilistic KW - Soil classification KW - Gaussian Process PY - 2024 SP - 1733 EP - 1740 AN - OPUS4-60712 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zinas, Orestis A1 - Papaioannou, Iason A1 - Schneider, Ronald A1 - Cuéllar, Pablo T1 - Spatial modeling of heterogeneous geotechnical site investigation data using multivariate Gaussian Process N2 - This presentation is part of the Engineering Risk Analysis group open seminars. It aims to showcase the results of an ongoing study centered on developing a novel probabilistic methodology for 3D geotechnical site characterization. This methodology integrates data from Cone Penetration Tests (CPTs) and categorical borehole data. The presentation covers the mathematical details of the proposed Multivariate Gaussian Process model and demonstrates its application to a real geotechnical site in New Zealand. T2 - ERA Seminars CY - Munich, Germany DA - 24.07.2024 KW - Geotechnical site-characterization KW - CPT KW - Boreholes KW - Gaussian Process PY - 2024 AN - OPUS4-60716 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo T1 - Geotechnical challenges in the field of Offshore Wind Energy. Micromechanical perspectives beyond the FEM N2 - This talk provides a brief overview on some geomechanical phenomena and problematic issues in the field of offshore wind-energy geotechnics, with reference to their associated challenges for a numerical analysis/simulation. These may include large deformations, fluid coupling and grain-scale phenomena, all of which are generally difficult to be addressed with conventional FE techniques. These challenges are illustrated here with a practical example for the retrofit of axially loaded piles using compaction grouting techniques. In this case, the mechanical effects of the retrofit may be analysed with standard FE techniques, but require the adoption of strong assumptions, while the injection process itself can only be analysed with special techniques such as the MPM. Finally, an LBM-DEM framework for the micromechanical analysis of such problems is introduced and a practical application for the estimation of the soil resistance to driving (SRD) in layered profiles is discussed. T2 - Online Symposium on Meshfree models for Engineers: Where are they really worthwhile? CY - Online meeting DA - 01.12.2022 KW - Offshore wind energy KW - Offshore geotechnics KW - Micromechanical simulation KW - LBM-DEM KW - Pile retrofit system PY - 2022 AN - OPUS4-56450 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Farhat, Abbas A1 - Philippe, Pierre A1 - Luu, Li-Hua A1 - Doghmane, Alexis A1 - Cuéllar, Pablo T1 - Hydraulic failure of granular materials with artificial cementation N2 - This paper presents an experimental study on the hydraulic failure of a submerged layer of cemented soil stressed by a localized upward water flow. Different mixtures of glass beads bonded with solid paraffin bridges were used as artificial material for the cemented granular soil. Variations in the cementation strength of the material were carefully introduced with different particle sizes and binder contents. The hydraulic fracture tests were then carried out with an upward flow injected at a controlled rate through a small section at the bottom of the samples. From a phenomenological perspective, the results reveal the existence of at least three modes of failure for a cemented soil layer: (1) overall block uplift, (2) block rupture by median crack at the inflow zone, and (3) progressive excavation of a fluidized path along the walls. The critical flow rate and pressure drop conditions at failure have been carefully quantified for the different mixtures and layer thicknesses, leading to a fair estimation of the hydraulic resistance of the samples, which here is found to be virtually independent of the grain size. However, the test results also showed inconsistent failure modes precluding so far the derivation of a simple phase diagram. Nevertheless, it was possible to rationalize all the measured data by employing appropriate modifications of the classical dimensionless numbers that describe the fluidization of purely frictional materials, whereby the cementation strength of the soil is quantified at the microscale through the yield tensile force of the intergranular bonds. Irrespective of its subsequent development, during which boundary conditions obviously play a major role, the initiation of the instability appears to take place very locally at the inlet when the drag force induced by the flow overcomes the cementation strength of the paraffin bonds. The results of this study thus appear to endorse the extension of the dimensional relationships of particulate systems in interaction with fluid flows to the case of cemented granular materials, in a similar vein as in recent previous studies. KW - Fluidized beds KW - Granular materials KW - Fluid Dynamics KW - Cemented soil PY - 2024 DO - https://doi.org/10.1103/PhysRevFluids.9.064305 SN - 2469-990X VL - 9 IS - 6 SP - 1 EP - 13 PB - American Physical Society AN - OPUS4-60803 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Brunier-Coulin, F. A1 - Cuéllar, Pablo A1 - Philippe, P. T1 - Generalized Shields criterion for weakly cohesive granular materials N2 - The erosion of natural sediments by a superficial fluid flow is a generic situation in many usual geological or industrial contexts. However, there is still a lack of fundamental knowledge about erosional processes, especially concerning the role of internal cohesion and adhesive stresses on issues such as the critical flow conditions for the erosion onset or the kinetics of soil mass loss. This contribution investigates the influence of cohesion on the surface erosion by an impinging jet flow based on laboratory tests with artificially bonded granular materials. The model samples are made of spherical glass beads bonded either by solid bridges made of resin or by liquid bridges made of a highly viscous oil. To quantify the intergranular cohesion, the capillary forces of the liquid bridges are here estimated by measuring their main geometrical parameters with image-processing techniques and using well-known analytical expressions. For the solid bonds, the adhesive strength of the materials is estimated by direct measurement of the yield tensile forces and stresses at the particle and sample scales, respectively, with specific traction tests developed for this purpose. The proper erosion tests are then carried out in an optically adapted device that permits a direct visualization of the scouring process at the jet apex by means of the refractive index matching technique. On this basis, the article examines qualitatively the kinetics of the scour crater excavation for both scenarios, namely, for an intergranular cohesion induced by either liquid or solid bonds. From a quantitative perspective, the critical condition for the erosion onset is discussed specifically for the case of the solid bond cohesion. In this respect, we propose here a generalized form of the Shields criterion based on a common definition of a cohesion number from yield tensile values, derived at both micro- and macroscales. The article finally shows that the proposed form manages to reconcile the experimental data for cohesive and cohesionless materials, the latter in the form of the so-called Shields curve along with some previous results of the authors which have been appropriately revisited. KW - Hydraulic jet erosion KW - Cohesive granular materials KW - Jet erosion test PY - 2020 DO - https://doi.org/10.1103/PhysRevFluids.5.034308 VL - 5 IS - 3 SP - 034308 PB - American Physical Society AN - OPUS4-50613 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo T1 - Deep foundations for offshore wind turbines. Part 2: Lateral behaviour and Advanced topics T1 - Cimentaciones profundas para aerogeneradores marinos. Parte 2: Comportamiento lateral y temas avanzados N2 - his presentation deals with the phenomenology and design of pile foundations for offshore wind turbines, and is divided into two lectures. The second lecture continues with the case of laterally loaded offshore piles, which bears most relevance for the case of the monopile foundations. Here again, a clear separation between physical reality and design methods is intended. Finally, the last part of the second lecture introduces several advanced topics which lie outside the classical design approaches, namely the hydromechanical coupling effects (i.e. the excess pore-pressure generation around the monopiles), the cyclic pile fatigue and the so-called pile setup (i.e. the time effects on the axial pile capacity). The relevance of the latter two topics is illustrated with experimental results from a field testing campaign on real large-scale piles. T2 - CEDEX-UNED 2021 Master course on Soil Mechanics and Geotechnical Engineering CY - Online meeting DA - 24.03.2021 KW - Offshore wind energy KW - Deep foundations KW - Offshore geomechanics KW - Lateral load bearing KW - Cyclic degradation KW - Pile ageing PY - 2021 AN - OPUS4-52342 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo T1 - Deep foundations for offshore wind turbines. Part 1: Axial behaviour T1 - Cimentaciones profundas para aerogeneradores marinos. Parte 1: Comportamiento axial N2 - This presentation deals with the phenomenology and design of pile foundations for offshore wind turbines, and is divided into two lectures. The first lecture presents a brief introduction to the context and peculiarities of such foundations, and then focuses on the particular case of axially loaded piles. This part is most relevant for the relatively slender piles of the multi-pile substructures (i.e. jackets and tripods). A clear distinction between physical phenomenology and practical design is drawn here. T2 - CEDEX-UNED 2021 Master course on Soil Mechanics and Geotechnical Engineering CY - Online meeting DA - 24.03.2021 KW - Offshore wind energy KW - Deep foundations KW - Offshore geomechanics KW - Axial load bearing KW - Design models PY - 2021 AN - OPUS4-52341 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Rücker, Werner A1 - Cuéllar, Pablo A1 - Georgi, Steven A1 - Karabeliov, Krassimire A1 - Baeßler, Matthias A1 - Johnsen, Björn ED - Durstewitz, M. ED - Lange, B. T1 - Please Avoid Tilting - Application-Oriented Design and Monitoring Model for Foundation Structures Subjected to Cyclic Loads N2 - A great deal is possible, even on the seabed. Together, wind and waves shake the foundations of the offshore wind turbines. "ere is also the “normal” current and ebb and #ow of the tides that are so distinctive in the North Sea. Pore water pressure can also occur on the seabed, loosening it. Where monopiles are involved, the worst case is that the stability of the whole turbine can be altered – even if such a monopile rammed into the seabed has a diameter of up to eight metres. Over half the planned offshore wind turbines in the North and Baltic Seas are to have monopile foundations, and over 40 % are to have multi-pile foundations, designed for example as a tripod. "is is why pile foundations and their loads deserve special attention. For one thing above all is to be avoided in plant operations, and that is the risk of turbine tilt. KW - Pile foundations KW - Offshore wind turbines KW - Cyclic loads PY - 2017 SN - 978-3-662-53178-5 DO - https://doi.org/10.1007/978-3-662-53179-2 SP - 53 EP - 59 PB - Springer AN - OPUS4-39340 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kullolli, Borana A1 - Cuéllar, Pablo A1 - Baeßler, Matthias T1 - On contact problem application for the local behavior of soil-pile interaction N2 - In this paper a shear test, which helps to study local behavior of the soil-pile interaction, is modelled numerically with the Finite Element Method as a 2D plane strain problem. A normal pressure on top and shear displacement on side were applied. So far, the material behavior was considered elastic for the sake of simplicity. The effect of thickness on contact elements and the presence of in plane stress has been highlighted. The purpose of the paper is to find a suitable contact element which represents more close to reality a soil-pile interaction problem under cyclic axial loading. Moreover, an insight on the presence of in-plane stress shows that it needs to be considered cautiously. T2 - ICCE2017 CY - Tirana, Albania DA - 12.10.2017 KW - Contact problem KW - Numerical modelling PY - 2017 SP - 167 EP - 174 PB - Polytechnic University of Tirana CY - Tirana, Albania AN - OPUS4-42962 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo T1 - Deep foundations for offshore wind turbines. Lecture 1: Axial behaviour T1 - Cimentaciones profundas para aerogeneradores marinos - Parte 1: Comportamiento axial N2 - This presentation deals with the phenomenology and design of pile foundations for offshore wind turbines, and is divided into two lectures. The first lecture presents a brief introduction to the context and peculiarities of such foundations, and then focuses on the particular case of axially loaded piles. This part is most relevant for the relatively slender piles of the multi-pile substructures (i.e. jackets and tripods). A clear distinction between physical phenomenology and practical design is drawn here. T2 - Masters course on Soil Mechanics and Geotechnical Engineering. Geotechnical Laboratory of CEDEX CY - Online meeting DA - 21.04.2020 KW - Pile foundations KW - Offshore wind turbines KW - Physical phenomenology KW - Design methods PY - 2020 AN - OPUS4-51057 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo T1 - Deep foundations for offshore wind turbines. Lecture 2: lateral behaviour and advanced topics T1 - Cimentaciones profundas para aerogeneradores marinos - Parte 2: Comportamiento lateral y tematica avanzada N2 - This presentation deals with the phenomenology and design of pile foundations for offshore wind turbines, and is divided into two lectures. The second lecture continues with the case of lateraly loaded offshore piles, which bears most relevance for the case of the monopile foundations. Here again, a clear separation between physical reality and design methods is intended. Finally, the last part of the second lecture introduces several advanced topics which lie outside the classical design approaches, namely the hydromechanical coupling effects (i.e. the excess pore-pressure generation around the monopiles), the cyclic pile fatigue and the so-called pile setup (i.e. the time effects on the axial pile capacity). The relevance of the latter two topics is illustrated with experimental results from a field testing campaign on real large-scale piles. T2 - Masters course on Soil Mechanics and Geotechnical Engineering. Geotechnical Laboratory of CEDEX CY - Online meeting DA - 21.04.2020 KW - Pile foundations KW - Offshore wind turbines KW - Physical phenomenology KW - Design methods PY - 2020 AN - OPUS4-51059 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo T1 - State of the art and development perspectives of deep foundations for offshore wind converters T1 - Estado del arte y perspectivas de desarrollo de las cimentaciones profundas para aerogeneradores offshore N2 - This presentation provides an overview of the main geotechnical aspects associated with deep foundations in the context of offshore wind generation. The most common deep foundation typologies (large diameter monopiles and multipile typologies) as well as new trends under development (e.g. suction buckets) and their current limits will be briefly described. The talk concludes with a brief review of advanced topics not covered in classical pile design, such as hydromechanical coupling effects (pore pressure generation), cyclic accumulation of deformations, cyclic degradation of axial capacity or pile-setup gains. T2 - Ciclo de Conferencias: Aplicaciones de la Geotecnia en la generación de Energía. Sociedad Argentina de Ingeniería Geotécnica SAIG CY - Online meeting DA - 02.12.2020 KW - Offshore wind energy KW - Deep foundations KW - Offshore geomechanics PY - 2020 AN - OPUS4-51729 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo T1 - An efficient GPU implementation of a micromechanical computational tool for erosion problems N2 - We present here a set of conceptual and numerical tools for a micromechanical simulation of general erosion problems involving fluid-saturated granular assemblies, whether frictional or cohesive. We propose a parallel computation using graphical processing units (GPUs) to treat large numbers of degrees of freedom with conventional desktop computers. The fluid phase is here simulated with a particle-resolved approach in the frame of the Lattice Boltzmann Method (LBM) while the granular solid phase is modelled as a collection of discrete particles from a Molecular Dynamics DEM perspective. The range of possible material behaviors for the solid granular phase is intended here to cover a broad spectrum from purely frictional to viscous cohesive materials with either brittle or transient debonding features. Specific details of the implementation and some validation cases will be put forward. To conclude we provide some exemplary applications in the field of soil erosion along with details on the parallel performance of the models. The results show that a micromechanical approach can be feasible and useful in practice, providing meaningful insights into complex phenomena like the erosion threshold and kinetics of weakly cemented soils. T2 - EWG-IE 2020 Workshop on "Innovative numerical methods for internal erosion processes" CY - Online meeting DA - 17.12.2020 KW - Erosion KW - Earthen hydraulic constructions KW - Micromechanical modelling KW - LBM-DEM coupling KW - GPU parallel computation PY - 2020 AN - OPUS4-51866 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Baeßler, Matthias A1 - Rücker, Werner A1 - Cuéllar, Pablo A1 - Georgi, Steven A1 - Karabeliov, Krassimire T1 - Large-scale testing facility for cyclic axially loaded piles N2 - Offshore piles have to withstand predominantly cyclic axial loads when they are installed in multi-pile configurations, as in jacket foundations. The dimensions of the pile are governed by both the internal capacity and the fatigue behaviour of the steel cross-section as well as by its external capacity in the pile-soil interaction. Owing to the large numbers of piled foundations required for current and future offshore wind farms, there is an urgent need to optimize the dimensions and related costs of single piles. With regard to the pile capacity, two major topics of research are the determination of possible capacity gains due to pile ageing effects and proper consideration of cyclic degradation. In order to investigate both effects, a large-scale testing facility has been constructed at the BAM TTS site in Horstwalde near Berlin. This open-air facility allows large tubular driven piles to be loaded cyclically in both tension and compression while studying the ageing effects by introducing delays between the testing campaigns. First results already show a moderate increase in pile capacity over time. Concerning the anticipated capacity degradation of cyclically loaded piles, preliminary results show an unexpected behaviour. Additional tests are currently being conducted for further clarification. KW - Steel driven piles KW - Offshore foundations KW - Cyclic axial loading KW - Pile ageing KW - Large-scale field testing PY - 2013 DO - https://doi.org/10.1002/stco.201310028 SN - 1867-0520 SN - 1867-0539 VL - 6 IS - 3 SP - 200 EP - 206 PB - Ernst & Sohn CY - Berlin AN - OPUS4-29535 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo T1 - Design challenges for Offshore wind-farms. From foundation mechanics to wind-farm aerodynamics N2 - This talk provides a brief introduction on general engineering design challenges for the offshore wind energy production. Some general features of the offshore wind-energy field from a civil engineering perspective are firstly presented, followed by a brief discussion of some of the main geomechanical issues for the foundation of the offshore turbines into the seabed. In the following part, an overview of relevant fluid-structure interactions and some options for an efficient numerical analysis are provided, where the hydromechanical Wave–Tower interaction is firstly discussed. Then, some general aspects of the windfarm aerodynamics are introduced. On the one hand, some modelling possibilities for the wake analysis of single turbines and turbine groups are discussed. And on the other hand the relevance of such analyses for a proper windfarm layout optimization is pointed out. In particular, this talk shows that: i) The bearing capacity of turbine multi-pile foundations can degrade under cyclic loading (waves, wind, …), while for monopile foundations cyclic hydromechanical coupling effects may take place, which may lead to a foundation softening; ii) Numerical analysis of a turbine’s interaction with wind/waves is useful and affordable, while simplified models can already provide a useful insight into the windfarm aerodynamics. iii) Turbulent wake analysis is very relevant for the windfarm layout. T2 - Colloquium "Energy systems compared", Winter semester 20/21, Faculty of Physics CY - Online meeting DA - 21.01.2021 KW - Offshore wind energy KW - Marine geotechnics KW - Fluid-structure interaction KW - Numerical modelling PY - 2021 AN - OPUS4-52038 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cuéllar, Pablo A1 - Baeßler, Matthias A1 - Georgi, Steven A1 - Rücker, Werner ED - Triantafyllidis, T. T1 - Special issues for the coupled transient simulation of laterally loaded offshore piles and novel experimental findings T2 - Workshop Gründung von Offshore-Windenergieanlagen CY - Karlsruhe, Germany KW - Offshore pile foundation KW - Cyclic lateral load KW - Pore pressure accumulation KW - Model testing PY - 2010 SN - 0453-3267 IS - 172 SP - 117 EP - 138 CY - Karlsruhe AN - OPUS4-24496 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo T1 - Computational models and experimental testing of offshore foundations at BAM - Current works and open issues T2 - BAM-DTU Seminar on Design and maintenance of support structures for Offshore Wind Converters CY - Copenhagen, Denmark DA - 2011-10-25 PY - 2011 AN - OPUS4-24737 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo T1 - Nuevos aspectos para el diseno estructural de generadores eólicos offshore en el Mar del Norte T2 - Workshop Fortnight of the Engineering (Quincena de la Ingenieria), Universidad de Cadiz UCA CY - Cadiz, Spain DA - 2012-03-20 PY - 2012 AN - OPUS4-25672 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Baeßler, Matthias A1 - Bronsert, Jeffrey A1 - Cuéllar, Pablo A1 - Rücker, Werner ED - Pombo, J. T1 - The stability of ballasted tracks supported on vibrating bridge decks, abutments and transition zones N2 - The track on bridges is affected by cyclic and dynamic action arising from the train passage and the reaction of the track supporting structure. Concerning the track, the current bridge design procedures include two major engineering tasks: On the one hand the stability of the track supported on the bridge deck has to be satisfied. In order to reduce the deterioration of the track the elasticity of the track has to be adapted for the stiff bridge deck. Furthermore, lateral stability has also to be satisfied. The vibration of the bridge structure has to be taken into account because it can affect the stability of the ballasted track. On the other hand the transition zone between bridge structure, abutment and the track on the subgrade is a matter of permanent concern. The changes in stiffness, in the dynamic behavior arising from the rolling stock and the relative deflection between the bridge structure and the abutment induce a nearly unavoidable problem for the long term behaviour on the track. BAM has conducted intensive experimental work to study the behaviour of the ballasted track on dynamically excited bridges. The state of the art is a design value for the deck acceleration of 0.35 g as established in the ENV 1991-1. In our experimental investigations the design value was verified. The influence of a frequency content higher than 30 Hz and of single vibration amplitudes on the track deterioration was evaluated. Both vertical and lateral stability were investigated. The influence of vibrations on the lateral stability can be more severe since the lateral stability could involve a sudden failure of the track. Furthermore, a simulation tool was developed to calculate the lateral stability on a vibrating bridge deck. For this simulation tool a parameter study was undertaken [1] where combinations of the curvature of the bridge-track system, the design temperature and the bridge deck vibrations were investigated. Parts of this study are incorporated in this paper. In a current research project the investigations are extended to the interaction of the train-track-dynamics and the long term behaviour of the transition zone. The main emphasis is on the integration of the possible deterioration of the structural components in the numerical modelling of the relevant structural elements of the vehicle, the bridge and bridge abutment structure. An outlook is given to a complete model for the assessment of the track behaviour at railway bridges. T2 - 1st international conference on railway technology: research, development and maintenance CY - Las Palmas, Gran Canaria, Spain DA - 18.04.2012 KW - Ballast KW - Acceleration KW - Bridge deck KW - Track deterioration KW - Track stability KW - Transition zone PY - 2012 SN - 978-1-905088-53-9 DO - https://doi.org/10.4203/ccp.98.13 SN - 1759-3433 N1 - Serientitel: Civil-Comp Proceedings – Series title: Civil-Comp Proceedings VL - 98 IS - Paper 13 SP - 1 EP - 20 PB - Civil Comp Press AN - OPUS4-26900 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Georgi, Steven A1 - Baeßler, Matthias A1 - Cuéllar, Pablo T1 - Verformungsakkumulation von Offshore-Pfahlgründungen unter zyklischer Belastung N2 - Die Berechnung von Verformungen lateral belasteter Pfahlgründungen bedingt in der Regel die Überführung der transienten Belastungen aus verschiedenen Umwelteinwirkungen in eine meist sinusförmige zyklische Belastung mit konstanter Amplitude. Dies bringt die Vernachlässigung der Reihenfolge, in der die realen Belastungen auftreten, mit sich. Die Voraussetzung dafür ist, dass der Einfluss dieser Reihenfolge auch tatsächlich gering ist. Da die meisten experimentellen Untersuchung hierzu sich auf die Elementebene und relativ geringe Zyklenzahlen beschränken, wird hier eine Versuchsserie präsentiert, in welcher Modellpfähle durch Zyklenpakete mit unterschiedlichen Amplituden in variierender Reihenfolge und hohen Lastspielzahlen belastet werden. Es zeigt sich ein geringer bis vernachlässigbarer Einfluss der Reihenfolge der Lastblöcke für reine Schwellbelastungen. T2 - 32. Baugrundtagung CY - Mainz, Germany DA - 2012-09-26 PY - 2012 SN - 9783981395358 SP - 97 EP - 104 CY - Essen AN - OPUS4-26769 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo A1 - Baeßler, Matthias A1 - Rücker, Werner T1 - Pore-pressure accumulation and soil softening around pile foundations for offshore wind turbines T2 - OMAE 2012 - 31st International conference on ocean, offshore and artic engineering CY - Rio de Janeiro, Brazil DA - 2012-07-01 KW - Offshore pile foundation KW - Cyclic loading KW - Coupled numerical modelling KW - Pore-pressure accumulation KW - Softening KW - Liquefaction PY - 2012 SN - 978-0-7918-4491-5 VL - 4 SP - 219 EP - 228 PB - ASME CY - New York, N.Y. AN - OPUS4-26738 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bronsert, Jeffrey A1 - Baeßler, Matthias A1 - Cuéllar, Pablo A1 - Rücker, Werner T1 - Numerische Modellierung der Fahrzeug-Fahrweg-Wechselwirkung an Brückenübergängen unter Berücksichtigung des Langzeitverhaltens N2 - In diesem Beitrag wird ein grundsätzliches Untersuchungskonzept für den Schienengebundenen Verkehr in Bezug auf das langzeitliche Verhalten am Brückenübergang vorgestellt. Das damit verbundene Ziel ist die Entwicklung eines numerischen Modells zu entwickeln, dass sowohl das Langzeitverhalten wie auch das kurzzeitdynamische Verhalten beschreibt, um konstruktive Lösungen zu entwickeln und zu optimieren. In einer ersten Phase wird der Brückenübergang mittels der FEM mit zwei unterschiedlichen Randmodellierungen für das FE-Gebiet modelliert. Die Ergebnisse der Modellierung mit einer Visko-Elastischen Randmodellierung und einer Randmodellierung mittels der Scaled-Boundary-Finite-Element Methode, werden miteinander verglichen. Unterschiede in der Wirkung auf kurzzeitdynamische Kenngrößen werden gezeigt, die heranzuziehen sind, um insbesondere Setzungen im Hinterfüllungsbereich des Brückenwiderlagers abzuschätzen. T2 - 4. VDI-Fachtagung - Baudynamik 2012 CY - Kassel, Germany DA - 25.04.2012 PY - 2012 SN - 978-3-18-092160-0 SN - 0083-5560 N1 - Serientitel: VDI-Berichte – Series title: VDI-Berichte VL - 2160 SP - 157 EP - 170 PB - VDI-Verl. CY - Düsseldorf AN - OPUS4-26980 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cuéllar, Pablo A1 - Baeßler, Matthias A1 - Georgi, Steven A1 - Rücker, Werner T1 - Porenwasserdruckaufbau und Bodenentfestigung um Pfahlgründungen von Offshore-Windenergieanlagen N2 - Die Gründung von Offshore-Windenergieanlagen erfordert oft die Installation von Stahl-Pfählen mit großem Durchmesser, entweder als Monopile- oder Mehrpfahl-Konfiguration (Jacket, Tripod, usw.). In dieser Veröffentlichung werden die Auswirkungen einer zyklischen lateralen Belastung auf Offshore-Pfahlgründungen untersucht. Hierbei wird besonderes Augenmerk auf die Entwicklung des Porenwasserdrucks im umgebenden gesättigten Boden gelegt. Es wird gezeigt, dass der progressive Aufbau von Porenwasserdruck zu erheblichen Veränderungen des Verhaltens der Gründung unter externer Belastung führen kann, die die Stabilität bzw. Gebrauchstauglichkeit der Anlage potenziell gefährden. Dazu werden auch einige Effekte, die während eines realistischen Sturms von moderater Stärke entstehen, untersucht. Die transiente Abminderung der Gründungssteifigkeit wird hierbei thematisiert. Die genannten Aspekte wurden von den Autoren mittels eines gekoppelten zweiphasigen numerischen Modells der Offshore-Gründung untersucht. Das verwendete Stoffgesetz für den Boden, im Rahmen der Theorie der verallgemeinerten Plastizität, kann wichtige Merkmale von zyklischem Bodenverhalten reproduzieren, wie z. B. die Tendenz zu einer fortschreitenden Verdichtung unter zyklischer Belastung, die für Verflüssigungsphänomene unter undränierten Bedingungen verantwortlich ist. Die Notwendigkeit der Verwendung eines solchen Ansatzes wird hier anhand von Vergleichsberechnungen mit einem einfacheren Stoffmodell bzw. mit einem ungekoppelten Modell erörtet. Abschließend werden einige Implikationen der untersuchten Fragenstellungen für die praktische Bemessung von Offshore-Monopiles diskutiert und spezifische Empfehlungen gegeben.--------------------------------------------------------------------------------------------------------------------------- For the installation of wind turbines in the offshore environment and their foundation in the seabed it is customary to employ large-diameter steel piles, either in monopile or multi-pile configurations (jacket, tripod, etc. ...). The effects of cyclic lateral loading on the offshore piles and particularly the possibility of a progressive accumulation of residual pore water pressure within the saturated embedding soil are discussed in this article. Here it is shown that this can lead to significant changes of their behaviour under external loading, which can potentially compromise the foundation's stability or serviceability. Furthermore, some of the singular effects arising during a realistic storm of moderate magnitude as well as their potential for transient damages to the foundation's stiffness are addressed in the paper. For the investigation of these phenomena the authors have employed a coupled bi-phasic analytical model of the offshore foundation. The constitutive model employed for the seabed, in the frame of the theory of Generalized Plasticity, can reproduce some complex features of cyclic soil behaviour such as the tendency for a progressive densification under cyclic loading, which is responsible for the soil liquefaction phenomena in undrained conditions. Finally, some implications and specific recommendations for the design of offshore monopiles in the frame of the limit states are provided. KW - Porenwasserdruckaufbau KW - Offshore-Pfahlgründung KW - Belastung KW - Zyklische KW - Pore pressure build-up KW - Offshore pile foundation KW - Cyclic loading PY - 2012 DO - https://doi.org/10.1002/bate.201200031 SN - 0932-8351 SN - 1437-0999 SN - 0005-6820 SN - 0341-1052 SN - 0932-6359 SN - 0932-8351 VL - 89 IS - 9 SP - 585 EP - 593 PB - Ernst & Sohn CY - Berlin AN - OPUS4-26981 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo T1 - Design challenges for offshore wind-farms. From foundation mechanics to wind-farm aerodynamics N2 - This talk provides a brief introduction on general engineering aspects of offshore wind energy production. Then some geomechanical issues for the foundation of OWTs into the seabed are introduced, while the results from experimental investigations and coupled computational analysis are discussed. In the second part of the seminar, the hydromechanical Wave–Tower interaction is firstly discussed. Then, some general aspects of the windfarm aerodynamics are introduced. On the one hand, some modelling possibilities for the wake analysis of single turbines and turbine groups are discussed. And on the other hand the relevance of such analyses for a proper windfarm layout optimization is pointed out. Concerning the geomechanical issues the talk shows that: i) The pile’s bearing capacity can degrade under cyclic loading (waves, wind, …). ii) The time effects can be relevant: Capacity improvement can be substantial, but also fragile. iii) There are cyclic PWP effects: Cyclic interaction with pore water may lead to soil softening and an uncoupled analysis (current design practice) is potentially unsafe. And concerning the hydromechanical and aerodynamical design considerations, this seminar shows that: i) Numerical analysis of turbine’s interaction with wind/waves is useful and affordable. ii) Simplified models can provide insight into windfarm aerodynamics. iii) Turbulent wake analysis is very relevant for the windfarm layout. T2 - Energy Science Kolloquium CY - Fakultät für Physik, Universität Duisburg-Essen, Germany DA - 25.01.2018 KW - Offshore wind farms KW - Geomechanics KW - Design PY - 2018 AN - OPUS4-43958 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Karabeliov, Krassimire A1 - Cuéllar, Pablo A1 - Baeßler, Matthias T1 - Großmaßstäbliche zyklische Versuche zum Zugtragverhalten von gerammten Stahlrohrpfählen N2 - Gerammte Stahlrohrpfähle sind das wesentlichste Gründungselement für Offshore-Konstruktionen. Typischerweise kommen diese als Monopiles oder als Mehrpfahlgründungen für Jacket-Konstruktionen zum Einsatz. Für die verhältnismäßig leichten Windenergieanlagen auf See wird bei Mehrpfahlgründungen regelmäßig die Zugtragfähigkeit maßgebend in der Bemessung. Zusätzlich sind Effekte aus wiederholten zyklischen Belastungen zu beachten, die sich auch auf die Zugtragfähigkeit auswirken können. Auch hier ergibt sich eine Besonderheit dadurch, dass im extremwertverteilten Lastspektrum wenige große (Wechsel-)Last-Amplituden entscheidend sind. Die gründungstechnischen Herausforderungen bei der Planung solcher Windparks auf See wurden von einer Reihe von Untersuchungen begleitet. Eine Versuchsserie zur Zugtragfähigkeit von großmaßstäblichen Pfählen wurde auf dem Testgelände der BAM nahe Horstwalde bei Berlin durchgeführt. Hierfür wurde ein Testfeld mit 10 Pfählen angelegt. Die Pfähle wurden monoton auf Zug und zyklisch belastet. Vergleichend wurden dynamische Pfahlprobebelastungen durchgeführt. Zwei der Pfähle wurden mit Dehnungssensoren instrumentiert und es konnte die Pfahl-Boden-Interaktion abschnittsweise ermittelt werden. T2 - 32. Christian Veder Kolloquium CY - Technische Universität Graz, Graz, Austria DA - 20.04.2017 KW - Offshore Windenergieanlagen KW - Pfahlgründungen KW - Zugtragfähigkeit KW - Zyklisches Tragverhalten PY - 2017 SN - 978-3-900484-75-0 IS - 58 SP - 103 EP - 120 PB - Gruppe Geotechnik Graz AN - OPUS4-40201 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo T1 - Großmaßstäbliche Versuche zum Zugtragverhalten von Rammpfählen N2 - Die Motivation für den hier vorgestellten Forschungsvorhaben liegt in den offenen Fragen bezüglich der Pfahlgründungen für Offshore Windenergieanlagen, die aktuell in zunehmender Zahl in den deutschen Gewässern installiert werden. Aus den unterschiedlichen Gründungsvarianten, die für den Offshore-Bereich normalerweise in Betracht kommen, zeichnen sich die Multi-Pfahl Varianten (also die Tripod- und Jacket-Gründungen) für eine vorwiegende axiale Komponente unter zyklischer Belastung aus. So werden die zyklische Momente aus Wind- und Wellenbelastung als zyklischen Kräftepaare an gegenüberliegenden Pfählen übertragen. Bei extremen Sturmereignissen können die Pfähle sogar aus den Druckbereich gezogen werden, was oft Bemessungsrelevant ist und technisch ein Neuland darstellt. Grundlegende Fragen zum Tragverhalten unter Zuglasten, wie z.B. die Minderung der Mantelreibung auf Zug oder die Möglichkeit einer zyklischen Degradation, bleiben noch offen und werden oft lediglich anhand von Annahmen berücksichtigt, wenn überhaupt. T2 - 32. Christian Veder Kolloquium - Zugelemente in der Geotechnik CY - Technische Universität Graz, Graz, Austria DA - 20.04.2017 KW - Offshore Windenergieanlagen KW - Pfahlgründungen KW - Zugtragfähigkeit KW - Zyklisches Tragverhalten PY - 2017 AN - OPUS4-40200 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo T1 - Deep foundations for offshore wind turbines T1 - Cimentaciones profundas para Aerogeneradores marinos N2 - In this lecture, both the physical behaviour and the general design procedures for deep foundations in the context of the offshore wind energy generation are presented. The first part of the lecture deals with the phenomenology and design of the pile foundations relative to the bearing of axial loads. The second part dwelves on the particularities of the lateral loads as well as on two research topics beyond the current design procedures, namely the hydromechanical coupling and the aging and fatigue phenomena as observed in the course of large-scale field tests. T2 - Internation Masters Course on Soil Mechanics and Geotechnical Engineering CY - Geotechnical Laboratory of CEDEX, Madrid, Spain DA - 27.03.2017 KW - Pile foundations KW - Offshore wind turbines KW - Axial and lateral design KW - Physical phenomenology PY - 2017 AN - OPUS4-39585 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Benseghier, Z. A1 - Cuéllar, Pablo A1 - Luu, L.-H. A1 - Delenne, J.-Y. A1 - Bonelli, S. A1 - Philippe, P. T1 - Relevance of Free Jet Model for Soil Erosion by Impinging Jets N2 - The surface erosion of soil samples caused by an impinging jet can be analyzed using the jet erosion test (JET), a standard experimental test to characterize the erosion resistance of soils. This paper specifically addresses the flow characteristics of a laminar impinging jet over the irregular surface of granular beds to discuss the pertinence and relevance of commonly used empirical estimations based on a selfsimilar model of a free jet. The JET is here investigated at the microscale with a coupled fluid-particle flow numerical odel featuring the lattice Boltzmann method (LBM) for the fluid phase combined with the discrete element method (DEM) for the mechanical behavior of the solid particles. The hydrodynamics of a laminar plane free jet are confronted with the results from a parametric study of jet impingement, both on solid smooth and fixed granular surfaces, that take into account variations in particle size, distance from jet origin, and jet Reynolds number. The flow characteristics at the bed surface are here quantified, including the maximal values in tangential velocity and wall shear stress, which can be regarded as the major cause of particle detachments under hydrodynamic solicitation. It is shown that the maximal velocity at the impinged surface can be described by the free jet self-similar model, provided that a simple empirical coefficient is introduced. Further, an expression is proposed for the maximal shear stress in laminar conditions, including a Blasius-like friction coefficient that is inversely proportional to the square root of the jet Reynolds number. To conclude, finally, the JET erosion of different cohesionless granular samples is analyzed, confirming that the threshold condition at the onset of granular motion is consistent with the Shields diagram and in close agreement with previous experimental results. KW - Lattice Boltzmann method KW - Soil erosion KW - Discrete element method KW - Laminar flow KW - Jet impingement PY - 2020 DO - https://doi.org/10.1061/(ASCE)HY.1943-7900.0001652 VL - 146 IS - 1 SP - 04019047 PB - ASCE AN - OPUS4-49491 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Cuéllar, Pablo A1 - Pastor, M. A1 - Mira, P. A1 - Fernández-Merodo, J.A. A1 - Baeßler, Matthias A1 - Rücker, Werner ED - Benz, T. ED - Nordal, S. T1 - Numerical investigations for the pile foundation of an offshore wind turbine under transient lateral load N2 - Numerical analysis can be useful for the investigation of important aspects of offshore foundation prototypes that otherwise could hardly be studied experimentally, like the evolution of pore-water pressure around the monopile foundation of an offshore wind turbine under extreme loading. A combination of mixed pressuredisplacement formulations along with a constitutive model for sands based on the Generalized Plasticity Theory can replicate accurately the soil behaviour in saturated conditions. However, additional issues must be taken into account in order to perform numerical simulations of offshore piles. Some implications of the Babuska-Brezzi restriction, as well as considerations about the pile-soil interface and suitable solution strategies are discussed here. Due to the high cost of the transient analysis, the parallel computation offers a promising perspective, but can be complex and needs to be implemented carefully in order to avoid a performance deterioration. A brief overview on current trends and functional software is given here. T2 - 7th European conference on numerical methods in geotechnical engineering (NUMGE 2010) CY - Trondheim, Norway DA - 2010-06-02 KW - Offshore pile foundation KW - Cyclic lateral load KW - Pore pressure accumulation PY - 2010 SN - 978-0-415-59239-0 SP - 913 EP - 919 PB - Taylor & Francis AN - OPUS4-21572 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo T1 - Numerical investigations for the pile foundation of an offshore wind turbine under transient lateral load. T2 - 7th European Conference on Numerical Methods in Geotechnical Engineering, NUMGE 2010 CY - Trondheim, Norway DA - 2010-06-04 PY - 2010 AN - OPUS4-21528 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo T1 - Special issues for the coupled transient simulation of laterally loaded piles and novel experimental findings. T2 - Workshop "Gründung von Offshore-Windenergieanlagen" CY - Karlsruhe, Germany DA - 2010-02-22 PY - 2010 AN - OPUS4-21253 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo T1 - Numerical procedures and experimental validation for structural dynamics T2 - Computational Engineering Department at CEDEX-CETA CY - Madrid, Spain DA - 2007-05-25 PY - 2007 AN - OPUS4-15005 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo T1 - Stoffmodell für Sande im Rahmen der "Generalized Plasticity" Theorie. Anwendungen und Implementierung für die Simulation von Offshore-Pfahlgründungen. T2 - Workshop des BMU-Forschungsverbundvorhabens "Pfahlgründungen von Offshore-Windkraftanlagen" im Rahmen der RAVE-Forschungsinitiative, BAM CY - Berlin, Germany DA - 2008-10-23 PY - 2008 AN - OPUS4-18638 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo T1 - CPT-based design for driven piles. Insight into the ICP method and general differences with UWA, NGI and FUGRO approaches T2 - Workshop des BMU-Forschungsvorhabens "Pfahlgründungen von Offshore-Windkraftanlagen" im Rahmen der RAVE-Forschungsinitiative, BAM CY - Berlin, Germany DA - 2008-10-23 PY - 2008 AN - OPUS4-18637 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo T1 - Numerical Investigations of an Offshore Pile Foundation - Preliminary results with GeHoMadrid FE Code T2 - 2. Workshop "Pfahlgründungen von Offshore-Windkraftanlagen", TU Berlin CY - Berlin, Germany DA - 2009-04-29 PY - 2009 AN - OPUS4-19490 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo T1 - Pile Foundations for Offshore Wind Turbines. Numerical and Experimental Investigations. T2 - 1st workshop "Research Cooperation CEDEX-BAM" CY - Madrid, Spain DA - 2009-07-07 PY - 2009 AN - OPUS4-19772 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo T1 - Numerical and Experimental Investigations for an Offshore Pile Foundation. T2 - 1st ALERT Olek Zienkiewicz Course on "Numerical Methods in Geomechanics" CY - Madrid, Spain DA - 2009-06-26 PY - 2009 AN - OPUS4-19771 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cuéllar, Pablo A1 - Baeßler, Matthias A1 - Rücker, Werner T1 - Ratcheting convective cells of sand grains around offshore piles under cyclic lateral loads N2 - Sand densification around the pile has traditionally been regarded as an explanation for the grain migration and soil subsidence that often occur around cyclic laterally loaded piles embedded in sand. Supported by new empirical evidence, this paper proposes that, additionally to some soil densification around the pile, the main cause for the continuous "steady-state" grain migration is a convective cell flow of sand grains in the vicinities of the pile head. Such convective flow would be caused by a ratcheting mechanism triggered by the cyclic low-frequency lateral displacements of the pile. Furthermore, the experimental results suggest that the limit between the convective cell and the static soil is marked by a distinct direct shear surface. This might shed some light into the complex phenomena related to the pile-soil interaction in the upper layers of the bedding, which are normally the main contributor for the lateral load-bearing capacity of piles. KW - Grain migration KW - Pile foundation KW - Cyclic lateral load KW - Ratcheting KW - Convection KW - Densification PY - 2009 DO - https://doi.org/10.1007/s10035-009-0153-3 SN - 1434-5021 SN - 1434-7636 SP - 1 EP - 12(?) PB - Springer CY - Berlin ; Heidelberg AN - OPUS4-20104 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo T1 - Investigaciones Numéricas y Experimentales para la Cimentación Offshore de Generadores Eólicos en el Mar del Norte T2 - Workshop "Quincena de la Ingenieria en la E.S.I., Escuela Superior de Ingenieria (ESI), Universidad de Cádiz" CY - Cadiz, Spain DA - 2010-03-11 PY - 2010 AN - OPUS4-21252 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo T1 - Pore-pressure-induced Softening and Long-Term Behaviour of Offshore Pile Foundations T2 - Workshop "Gründungen von Offshore-Windenergieanlagen", TU Berlin CY - Berlin, Germany DA - 2011-03-22 PY - 2011 AN - OPUS4-23561 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bronsert, Jeffrey A1 - Baeßler, Matthias A1 - Cuéllar, Pablo A1 - Rücker, Werner T1 - Bewertung und Optimierung von Brückenübergangsbereichen auf der Basis eines numerischen Modells für die Fahrzeug-Fahrweg-Brücken-Wechselwirkung N2 - In diesem Artikel wird ein 3D FE-Modell für den Brückenübergangsbereich vorgestellt, das eine Bewertung hinsichtlich des Langzeitverhaltens ermöglicht und an dem Optimierungsmaßnahmen diskutiert werden können. Bestandteile des numerischen Modells sind das Fahrzeug-Fahrwegmodell mit Brückenstruktur und eine Randformulierung mit der SBFEM. Die hier diskutierten Optimierungsmaßnahmen fokussieren sich auf eine reine Anpassung der Fahrwegsteifigkeit durch elastische Elemente auf der Brückenstruktur. T2 - 5. VDI-Fachtagung - Baudynamik 2015 CY - Kassel, Germany DA - 22.04.2015 PY - 2015 SN - 978-3-18-092244-7 N1 - Serientitel: VDI-Berichte – Series title: VDI-Berichte IS - 2244 SP - 247 EP - 258 PB - VDI-Verl. CY - Düsseldorf AN - OPUS4-35259 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Taylor, G.R. A1 - Tan, R. A1 - O´Brien, A.S. A1 - Baeßler, Matthias A1 - Cuéllar, Pablo A1 - Lane, J.S. A1 - Evans, E. T1 - The use of physical model testing in the development of models for potential impact assessment on the UK rail network N2 - Most railway embankments in the UK were built in the Victorian era and are of end-tipped construction using materials (usually cohesive) excavated from adjacent cuttings, resulting in a clod-and-matrix structure. Historically, there has been a lack in understanding of the mechanical behaviour of such railway embankments. In the next decade railway traffic in the UK, particularly freight, is forecast to grow considerably. Consequently, there is a need to improve the understanding of how increases in rail traffic loading may influence the mechanical behaviour of railway embankments and thus track performance. The Rail Safety and Standards Board in conjunction with Network Rail is currently undertaking a programme of applied research into this topic. As part of these studies a programme of physical model tests has been carried out. Physical model tests can provide high quality data on system performance under a large range of loading conditions and geometrical configurations. The data can be generated rapidly, with test periods of weeks or months rather than years or decades. Additionally, boundary conditions are well-defined and controlled, compared with the complex situations encountered in full scale embankments in the field. This paper summarises the physical model test programme, the development of the test set-up, the tests themselves and the conclusions drawn. T2 - European Conference on Soil Mechanics and Geotechnical Engineering CY - Edinburgh, Scotland, UK DA - 13.09.2015 KW - Railway embankment KW - Clay fill KW - Physical model testing PY - 2015 SN - 978-0-7277-6067-8 DO - https://doi.org/10.1680/ecsmge.60678 SP - 361 EP - 366 AN - OPUS4-39374 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Baeßler, Matthias A1 - Cuéllar, Pablo A1 - Georgi, Steven A1 - Karabeliov, Krassimire A1 - Rücker, Werner A1 - Johnsen, Björn ED - Durstewitz, M. ED - Lange, B. T1 - „Neuland“ auf dem Meeresboden - Überwachungsverfahren und Bewertungsmodell für die Gründung von Offshore-Windenergieanlagen N2 - Offshore-Windenergie betritt Neuland, gerade bei der Gründung. Denn Windenergie auf See kann die Erfahrungen der gängigen Offshore-Konstruktionen der Öl- und Gasindustrie nur bedingt nutzen. Mehr als dort, versucht man bei der Offshore-Windenergie, die Gründungsabmessungen – insbesondere die Pfahllängen – soweit wie möglich zu reduzieren. Denn dies kann bei der hohen Anzahl der Windenergieanlagen erhebliche wirtschaftliche Vorteile bringen. Andererseits wird die Standsicherheit der Gründungen durch den viel höheren Anteil an zyklischen Lasten gegenüber den gängigen Offshore- Strukturen in schwer einschätzbarer Weise zusätzlich gefährdet. Da Offshore-Windenergieanlagen in Serienfertigung produziert werden, wirkt sich hier jeder systematische Fehler bei der Gründung dann gleich als Serienfehler auf eine Vielzahl von Anlagen aus. Überwachung ist also angesagt – und das richtige Maß bei der Pfahlgründung, der am meisten verwendete Fundamenttyp bei Windenergieanlagen. KW - Offshore Windkraftanlagen KW - Pfahlgründungen KW - Überwachungsverfahren PY - 2016 SN - 978-3-658-09782-0 SN - 978-3-658-09783-7 DO - https://doi.org/10.1007/978-3-658-09783-7 SP - 61 EP - 68 PB - Springer AN - OPUS4-39348 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -