Today
Bookmark and Share    
See detailIntegrated micromechanical model for slope stability analysis
Kabore, Brice Wendlassida UL; Peters, Bernhard UL

Scientific Conference (2019, April 09)

Advances in supercomputing hardware have made it possible to handle highly complex geomechanical analysis with large data. Thus, particle-based methods are gaining an ever-increasing interest with ... [more ▼]

Advances in supercomputing hardware have made it possible to handle highly complex geomechanical analysis with large data. Thus, particle-based methods are gaining an ever-increasing interest with massively parallel programs being developed. These methods have been applied to the analysis of failure mechanisms and scenarios such as mass movement in landslides, avalanches under static, dynamic or seismic loading condition. They provide deep insights into the meso and micro-scale mechanisms leading to macroscopic instabilities. This contribution describes a micromechanical model for stability analysis and simulation in natural or man-made slopes under complex loading and boundary conditions. Based on the micromechanics of loose granular and compacted geomaterial, microstructural change, viscoelastic deformations, fracture, and healing are explicitly integrated into a coupled discrete particle and beam lattice model. Stress-based failure criteria and energy based dissipation and frictional contact are employed. Both gravity increase and strength reduction methods have been employed to evaluate the Factor of Safety (FoS) and potential failure surface and compared. With an emphasis on the impact of the microstructure and its spatial variability on stress-induced microcracks and crack propagation, this study outlines material models and properties relevant to stability analysis. Special focus has been put on layered slopes which present varying shear strength along the depth formed over time according to pressure, temperature, and moisture such as snowpack. This microstructural approach unifies geometrical and material information and allows the structural assembling layers of different strength. [less ▲]

Detailed reference viewed: 56 (11 UL)
See detailFemmes et informatique de la seconde guerre mondiale aux années 1980
Schafer, Valerie UL

Conference given outside the academic context (2019)

Au cours de cette table ronde, il s'agira d'interroger "l'âge d'or" des femmes dans l'informatique, de questionner des formes d'empowerment mais aussi d'invisibilisation des femmes et les premiers pas ... [more ▼]

Au cours de cette table ronde, il s'agira d'interroger "l'âge d'or" des femmes dans l'informatique, de questionner des formes d'empowerment mais aussi d'invisibilisation des femmes et les premiers pas vers la masculinisation de "l'informatique" (notion également à historiciser). [less ▲]

Detailed reference viewed: 45 (7 UL)
See detailDu papier aux données
Schafer, Valerie UL

Conference given outside the academic context (2019)

Ce discours proposait un parcours historique au cœur de 50 ans d’invention et de ré-invention de l’Office des publications de l'Union Européenne, et ce à la croisée de l’histoire européenne et de ... [more ▼]

Ce discours proposait un parcours historique au cœur de 50 ans d’invention et de ré-invention de l’Office des publications de l'Union Européenne, et ce à la croisée de l’histoire européenne et de l’histoire des réseaux et technologies numériques. L’Office est en effet un point d’observation privilégié de ces évolutions, qui bien sûr ne sont pas linéaires et connaissent des temps de doutes comme d’accélération. [less ▲]

Detailed reference viewed: 33 (2 UL)
See detailPost-Brexit regulatory arbitrage: Basic instincts never change
Asimakopoulos, Ioannis UL

in BrieFin - EBI Newsletter (2019)

Detailed reference viewed: 30 (1 UL)
Full Text
See detailLa proposition franco-allemande d'un instrument budgétaire pour la zone euro: le "millefeuille" continue
Allemand, Frederic UL

in Revue de l'euro (2019)

Le 22 février 2019, la France et l'Allemagne ont diffusé le texte arrêté en commun la veille sur les principales caractéristiques d'un instrument budgétaire de convergence et de compétitivité pour la zone ... [more ▼]

Le 22 février 2019, la France et l'Allemagne ont diffusé le texte arrêté en commun la veille sur les principales caractéristiques d'un instrument budgétaire de convergence et de compétitivité pour la zone euro. Ce document vise à nourrir les réflexions de l'Eurogroupe sur le sujet, ainsi que le Sommet de la zone euro de décembre 2018 en a chargé ce dernier. [less ▲]

Detailed reference viewed: 36 (1 UL)
Full Text
Peer Reviewed
See detailMULTI-SCALE MODELLING OF SNOW MECHANICS
Kabore, Brice Wendlassida UL; Peters, Bernhard UL; Willibald, C. et al

in 41st Solid Mechanics Conference (2018, August 27)

Detailed reference viewed: 14 (2 UL)
Full Text
See detailMicromechanical model for sintering and damage in viscoelastic porous ice and snow. Part I: Theory
Kabore, Brice Wendlassida UL; Peters, Bernhard UL

E-print/Working paper (2018)

Ice and snow have sometime been classified as a viscoelastic or viscoplastic mate- rial according to temperature, strain rate, pressure and time scale. Throughout experimental studies presented in the ... [more ▼]

Ice and snow have sometime been classified as a viscoelastic or viscoplastic mate- rial according to temperature, strain rate, pressure and time scale. Throughout experimental studies presented in the literature, it has been observed that at very low temperatures or high strain rate, porous ice and snow exhibit brittle behavior, but experience high viscous and plastic flow at temperatures closed to the melting point and low rates. At the macroscopic level nonlinearity is not necessarily attributed to material level permanent changes or yielding but mainly to micro cracks, porosity collapse and crack propagation. This paper attempts to address this complex behavior with a full microstructure based model. [less ▲]

Detailed reference viewed: 20 (3 UL)
Peer Reviewed
See detailBonded Particle Model for Numerical Analysis of Concrete Fracture under Impact Loading
Kabore, Brice Wendlassida UL; Peters, Bernhard UL

Scientific Conference (2018, July 04)

Linear elastic fracture mechanics and homogenization techniques have shown limitations in concrete fracture analysis due to the existence of localized damage zone and instabilities near the crack region ... [more ▼]

Linear elastic fracture mechanics and homogenization techniques have shown limitations in concrete fracture analysis due to the existence of localized damage zone and instabilities near the crack region. Concrete structures which are primarily quasi-brittle material present rate dependent failure modes, and fracture properties under impact or blast loading. Experiments show that concrete may exhibit viscoplasticity, strain rate and hydrostatic pressure dependent damage and crack propagation. This paper describes an explicit approach of discrete particles bonded with Euler-Bernoulli beams to simulate dynamic fracture in concrete. The fracture is initiated in the beam network and propagated and energy is dissipated according to the prescribed fracture energy. The bonded particle model has shown advanced capability to predict processes including microcracking, crack deflection, bridging and branching occurring in the fracture process zone under impact loading. It can also predict to some extent the crack propagation velocity. A quasi-brittle fracture model with rate dependent strength is elaborated to capture rate dependent behavior at high and moderate strain rates where the concrete exhibit increased load carrying capacity. In order to ensure stability of this program, numerical localnon viscous damping is used. The effect of particle size and bonds in overall response was also investigated. [less ▲]

Detailed reference viewed: 18 (2 UL)
See detailChallenges and Trends in Enforcing Economic and Financial Crime: Criminal Law and Alternatives in Europe and the US
Ligeti, Katalin UL; Tosza, Stanislaw

in Ligeti, Katalin; Tosza, Stanislaw (Eds.) White Collar Crime. A Comparative Perspective (2018)

This chapter by Katalin Ligeti and Stanislaw Tosza provides a synthesis of the main findings of the book edited by the two authors (White Collar Crime. A Comparative Perspective, Hart Publishing, 2018 ... [more ▼]

This chapter by Katalin Ligeti and Stanislaw Tosza provides a synthesis of the main findings of the book edited by the two authors (White Collar Crime. A Comparative Perspective, Hart Publishing, 2018). The chapter first presents the challenges in investigating and prosecuting economic and financial crime (section II). The analysis of four national systems (France, Poland, Sweden, and the US) complemented by the information provided in the transversal chapters led to the identification of four major tendencies in the field in response to these challenges (section III): the swinging of enforcement strategies between prosecuting individuals or/and corporations (section III.A); the extension of punitive sanctions and the use of compliance programmes as punishment (section III.B); the extensive use of alternatives to criminal proceedings (section III.C); and the increased role of private actors in controlling economic and financial crime (section III.D). In section 4, these responses are scrutinised from the perspective of the human rights regime. [less ▲]

Detailed reference viewed: 37 (0 UL)
See detailDynamic Sintering of a High Temperature Granular Material: Experiments and Simulations
Willivald, Carolin; Kabore, Brice Wendlassida UL; Szabó, Denes et al

Scientific Conference (2017, September 26)

Snow changes from a porous solid to a granular material during deformation with high strain rates. This transition occurs in many cases where snow is relevant to engineering problems (vehicle mobility ... [more ▼]

Snow changes from a porous solid to a granular material during deformation with high strain rates. This transition occurs in many cases where snow is relevant to engineering problems (vehicle mobility, avalanche formation and prevention, skiing etc.). For the description of the fast deformation of snow the discrete element method (DEM) is a valuable tool, as it is able to account for both states and the transition between them: the interaction of the loose and bonded particles. For the development of a physically relevant DEM snow model [1] we investigate experimentally along with simulations the basic processes of the granular behavior of snow. In the granular state, sintering plays an important role for the dynamics of the particles. Via sintering the high temperature ice particles (homologous temperature 0.95) bond together and change the structure and the physical properties of the material. This temperature dependent sintering process, which happens in the time range of milliseconds to hours, is in the focus of the present work. The fast sintering of ice in the range of milliseconds has scarcely been investigated. However, from sintering studies with ice cones (radius of 3 mm) we know, that the sintering force is closely related to the contact area of the particles [2]. As the contact area changes considerably for complicated shapes, exhibited by natural snow crystals, we consider different snow types (grain shape and size), besides ice beads as spherical model snow. The latter one is used to exclude shape effects and to directly compare experiments to simulations with spherical particles. To be able to take the effects of the grain shape into account and to examine sintering in the time range of interest (seconds), we perform angle of repose experiments and simulations. Snow is sieved to pile up on a flat base until an angle of equilibrium, the angle of repose, is formed. This angle increases with the sintering of the particles, but also with the inter-particle friction. To analyze the contribution of the friction and the grain shape without sintering, we perform the experiments at a low temperature °C ( 0.87), where sintering can be neglected; thus, the angle of repose is determined by inter-particle friction. With these measurements, we calibrate the simulations. At higher temperatures (up to °C) sintering changes the angle of repose, and a physically relevant sintering law for real snow is established in the simulations. [less ▲]

Detailed reference viewed: 16 (3 UL)