TY - CONF A1 - Sanayei, Mohammad Hassan A1 - Farhat, A. A1 - Luu, L.-H. A1 - Werner, L. A1 - Rettinger, C. A1 - Philippe, P. A1 - Cuéllar, Pablo T1 - Micromechanical framework for a 3d solid cohesion model - implementation, validation and perspectives N2 - This article presents a solid cohesion model for the simulation of bonded granular assemblies in the frame of 3D discrete element approaches (DEM). A simple viscoplastic cohesion model for 2D geometries is extended to 3D conditions, while its yield criterion is generalized as a hyper-surface in the space of bond solicitations to include torsional moments. The model is then calibrated using experimental results of uniaxial traction at both the microscopic and macroscopic scales with an artificial granular cohesive soil. The paper finally presents some simulated results on the macromechanical sample traction application and briefly discusses the model's current limitations and promising prospects for subsequent works. T2 - VII International Conference on Particle-Based Methods PARTICLES 2021 CY - Hamburg, Germany DA - 04.10.2021 KW - Granular Cohesive Materials KW - DEM KW - Micromechanical Tensile Failure KW - Macromechanical Sample Strength PY - 2021 SP - 1 EP - 10 AN - OPUS4-53716 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schneider, Ronald A1 - Cuéllar, Pablo A1 - Baeßler, Matthias T1 - Probabilistic approaches to the design and assessment of offshore foundations considering spatially varying site conditions N2 - In this contribution, we consider two applications in which probabilistic approaches can potentially complement or enhance the design and assessment of offshore wind turbine foundations. First, we illustrate in a numerical example that probabilistic modelling can be helpful in dealing with chang-es in turbine locations during the planning phase of an offshore wind farm. In this case, spatial probabilistic modelling of the ground conditions enables (a) an inference of the soil properties at the modified turbine location from field data collected at different locations across an offshore wind farm site and (b) an optimisation of further site investigations. Second, we discuss the uncer-tainties and risks associated with the installation of large diameter monopiles in soils with hetero-geneities such as strong layers and/or embedded boulders. Subsequently, we present a concept for modelling, understanding, and managing these risks based on a probabilistic model of the subgrade conditions, monopile, and subgrade-pile-interaction. T2 - 3rd International Conference on Structural Integrity for Offshore Energy Industry (SI 2021) CY - Online meeting DA - 15.11.2021 KW - Probabilistic modelling KW - Spatially varying ground conditions KW - Foundation reliability analysis KW - Monopile installation risks PY - 2022 SN - 978-1-8383226-3-2 SP - 9 EP - 17 AN - OPUS4-54531 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo A1 - Benseghier, Z. A1 - Luu, L.-H. A1 - Bonelli, S. A1 - Delenne, J.-Y. A1 - Radjai, F. A1 - Philippe, P. T1 - Numerical insight into the micromechanics of jet erosion of a cohesive granular material N2 - Here we investigate the physical mechanisms behind the surface erosion of a cohesive granular soil induced by an impinging jet by means of numerical simulations coupling fluid and grains at the microscale. The 2D numerical model combines the Discrete Element and Lattice Boltzmann methods (DEM-LBM) and accounts for the granular cohesion with a contact model featuring a paraboloidal yield surface. Here we review first the hydrodynamical conditions imposed by the fluid jet on a solid granular packing, turning then the attention to the impact of cohesion on the erosion kinetics. Finally, the use of an additional subcritical debonding damage model based on the work of Silvani and co-workers provides a novel insight into the internal solicitation of the cohesive granular sample by the impinging jet. T2 - 8th International Conference on Micromechanics on Granular Media CY - Montpellier, France DA - 03.07.2017 KW - Micromechanical modelling KW - LBM-DEM KW - Jet erosion KW - Granular cohesion KW - Subcritical debonding PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-411186 DO - https://doi.org/10.1051/epjconf/201714015017 VL - 140 SP - Paper 15017, 1 EP - Paper 15017, 4 PB - The European Physical Journal (EPJ) - Web of Conferences AN - OPUS4-41118 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Brunier-Coulin, F. A1 - Sarrat, J.-L. A1 - Cuéllar, Pablo A1 - Philippe, P. T1 - Experimental investigation of impinging jet erosion on model cohesive granular materials N2 - Erosion of soils affects both natural landscapes and engineering constructions as embankment dams or levees. Improving the safety of such earthen structures requires in particular finding out more about the elementary mechanisms involved in soil erosion. Towards this end, an experimental work was undertaken in three steps. First, several model materials were developed, made of grains (mostly glass beads) with solid bridges at particle contacts whose mechanical yield strength can be continuously varied. Furthermore, for most of them, we succeeded in obtaining a translucent system for the purpose of direct visualization. Second, these materials were tested against surface erosion by an impinging jet to determine a critical shear stress and a kinetic coefficient. Note that an adapted device based on optical techniques (combination of Refractive Index Matching and Planar Laser Induced Fluorescence) was used specifically for the transparent media. Third, some specifically developed mechanical tests, and particularly traction tests, were implemented to estimate the mechanical strength of the solid bridges both at micro-scale (single contact) and at macro-scale (sample) and to investigate a supposed relationship with soil resistance to erosion. T2 - 8th International Conference on Micromechanics on Granular Media CY - Montpellier, France DA - 03.07.2017 KW - Erosion onset KW - Experimental testing KW - Cohesive granular media KW - RIM-PLIF techniques PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-411215 DO - https://doi.org/10.1051/epjconf/201714008002 VL - 140 SP - Paper 08002, 1 EP - Paper 08002, 4 PB - The European Physical Journal (EPJ) - Web of Conferences AN - OPUS4-41121 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Philippe, P. A1 - Cuéllar, Pablo A1 - Brunier-Coulin, F. A1 - Luu, L.-H. A1 - Benahmed, N. A1 - Bonelli, S. A1 - Delenne, J.-Y. T1 - Physics of soil erosion at the microscale N2 - We focus here on the major and still relevant issue of soil erosion by fluid flows, and more specifically on the determination of both a critical threshold for erosion occurrence and a kinetics that specifies the rate of eroded matter entrainment. A state-of-the-art is first proposed with a critical view on the most commonly used methods and erosion models. It is then discussed an alternative strategy, promoting the use of model materials that allow systematic parametric investigations with the purpose of identifying more precisely the local mechanisms responsible for soil particle erosion and ultimately quantifying both critical onsets and kinetics, possibly through existing or novel empirical erosion laws. Finally, we present and discuss several examples following this methodology, implemented either by means of experiments or numerical simulations, and coupling erosion tests in several particular hydrodynamical configurations with wisely selected mechanical tests. T2 - 8th International Conference on Micromechanics on Granular Media CY - Montpellier, France DA - 03.07.2017 KW - Erosion phenomena KW - Onset of jet erosion KW - LBM-DEM numerical simulation KW - Experimental testing KW - PLIF-RIM optical techniques PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-411198 DO - https://doi.org/10.1051/epjconf/201714008014 VL - 140 SP - Paper 08014, 1 EP - Paper 08014, 4 PB - The European Physical Journal (EPJ) - Web of Conferences AN - OPUS4-41119 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rücker, Werner A1 - Karabeliov, Krassimire A1 - Cuéllar, Pablo A1 - Baeßler, Matthias A1 - Georgi, Steven ED - Savidis, S.A. T1 - Ermittlung der Tragfähigkeit von Offshore Rammpfählen unter zyklischer Belastung - Modellversuche, Großversuche, numerische Verfahren N2 - Im Rahmen mehrerer vom BMU geförderter Forschungsvorhaben untersucht die BAM zusammen mit Partnern aus Industrie und Wissenschaft das Tragverhalten von zyklisch lateral und axial belasteten Rammpfählen für Offshore Windkraftanlagen. Neben Modellversuchen im Labor werden hierbei auch Großversuche im Maßstab 1: 2 und im Originalmaßstab durchgeführt. In diesen Großversuchen werden Parameter wie Tragfähigkeitsminderung infolge zyklischer Lasten im Druck- und Schwellbereich, sowie die Zunahme von Tragfähigkeiten durch sogenannte Anwachseffekte untersucht. Durch die zyklischen Belastungen werden insbesondere als unsicher anzunehmende Wertepaare in den derzeit verwendeten Interaktionsdiagrammen untersucht, wobei ein Hauptaugenmerk aber nicht nur auf dem Versagen des Pfahls, sondern auch auf der Ermittlung der Resttragfähigkeit nach definierten Zyklenzahlen liegt. Ein weiteres Ziel ist, die sich am Pfahlmantel in Abhängigkeit der oben genannten Parameter ergebenden Tragfähigkeiten durch numerische Berechnungen und durch Laborversuche zu erklären und ein existierendes Modell zur Ermittlung der Tragfähigkeit unter zyklischer Belastung auf der Grundlage aktueller Messdaten am Pfahl zu validieren und zu kalibrieren. Weiterhin finden durch den Projektpartner BARD Untersuchungen zur Abhängigkeit der Pfahltragfähigkeit von der Standzeit bei der Errichtung des Windparks BARD Offshore 1 statt. T2 - 8. Hans Lorenz Symposium CY - Berlin, Germany DA - 11.10.2012 PY - 2012 SN - 978-3-8440-1377-1 SN - 0342-3905 N1 - Serientitel: Veröffentlichungen des Grundbauinstitutes der Technischen Universität Berlin – Series title: Veröffentlichungen des Grundbauinstitutes der Technischen Universität Berlin IS - 60 SP - 311 EP - 329 PB - Shaker AN - OPUS4-27178 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kullolli, Borana A1 - Baeßler, Matthias A1 - Cuéllar, Pablo A1 - Rica, S. A1 - Rackwitz, F. T1 - An enhanced interface model for friction fatigue problems of axially loaded piles N2 - 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. T2 - Conference: OMAE CY - Glasgow, Scotland, UK DA - 09.06.2019 KW - Soil-structure interaction KW - Interface PY - 2019 VL - 2019 SP - Article Number: UNSP V001T10A013 PB - ASME CY - Glasgow, Scotland AN - OPUS4-48444 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 - Kullolli, Borana A1 - Cuéllar, Pablo A1 - Baeßler, Matthias A1 - Stutz, H. H. T1 - Modelling and calibration for cyclic soil-structure interface behaviour N2 - The structural performance of many geotechnical systems (e.g. axially-loaded pile foundations), depends on the shearing resistance at the soil interface, which may govern the load bearing capacity of the foundation. Experimental investigations have shown that this interaction is mainly localised within a narrow shear band next to the structure. Under cyclic loading, a contraction of the soil at the interface may arise (net volume loss), possibly leading to a stress relaxation and thus to a reduction of the load bearing capacity (the so-called friction fatigue). Based on the constitutive similarities between soil continua and interfaces, we propose here the adaption of a Generalized Plasticity model for sandy soils for the numerical analysis of interface problems. In this contribution, the results of an experimental campaign for the parameter calibration of the constitutive model are presented. The tests have been conducted with a ring shear device involving different normal stresses, roughness of the steel plates as well as cyclic loading. The new modelling approach shows promising results and has the additional practical advantage that the interface zone and the soil continuum can both be described with the same constitutive model in general boundary value problems. T2 - Konferenz 7th International Symposium on Deformation Characteristics of Geomaterials CY - Glasgow, Scotland DA - 26.06.2019 KW - Soil-structure interaction KW - Offshore foundations PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-489096 DO - https://doi.org/10.1051/e3sconf/20199213007 VL - 92 SP - 13007 EP - 13013 PB - EDP Sciences CY - Glasgow, Scotland AN - OPUS4-48909 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -