Das Projekt "Verwendung des GWR II im Rahmen der Hochwasser-Risikoanalyse" wird vom Umweltbundesamt gefördert und von Universität für Bodenkultur Wien, Institut für Alpine Naturgefahren durchgeführt. Ziel des Auftraggebers ist es, eine konzeptionelle Grundlage zu Hand zu haben, die Auskunft über die Verwendungsmöglichkeiten des GWR II im Rahmen der Hochwasser-Risikoanalyse gibt. Des Weiteren soll ein Überblick zu weitergehenden Anwendungen im Rahmen der EU-Hochwasserrichtlinie (2007/60/EG) gegeben werden. Hierbei sollen vor allem das kurz- und langfristige Potential sowie mögliche Synergieeffekte mit Planungsinstrumenten der Schutzwasserwirtschaft im Vordergrund stehen, sowie ein Ausblick auf eine mögliche technische Umsetzung und Implementierung.
Das Projekt "Dynamic Properties of Granular Soils and Behavior of Earth Structures under Strong Earthquake Motion" wird vom Umweltbundesamt gefördert und von Ecole Polytechnique Federale de Lausanne, Institut des sols, roches et fondations, Laboratoire de mecanique des sols durchgeführt. Seismic wave propagation in granular soils can induce large strain amplitudes in case of strong earthquakes. Seismic motions are irregular in frequency content and in amplitude, and have three different components in orthogonal directions. In this context, the main objective of this PhD research deals with nonlinear effects observed in granular soils under such complex loadings. A dynamic triaxial press was developed for dry and undrained saturated sand samples. Axial and lateral stresses can be applied independently with large amplitudes for various loading shapes. An innovative laser-based non-contact measurement technique was developed to continuously monitor the sample radius Dry and undrained cyclic tests performed on Leman Sand at various frequencies from 0.1 to 6.5 Hz show that the behaviour of this granular material is frequency-dependent at medium to large strains. Sand stiffness, which depends on stress conditions, seems to influence the extent of frequency effects on soil behaviour: for tests with lower stiffness, the soil response to low frequency is significantly amplified compared to the high frequency range. The overall rate-sensitivity may be enhanced by the angularity of the grains. Other cyclic undrained saturated tests on Leman Sand demonstrate that the superposition of two different loadings, one axial and one lateral (bidirectional tests), induce coupling effects in the nonlinear soil response. Experimental results are finally modelled with the linear equivalent method and with a multi-mechanism elastoplastic model (ECP Hujeux). Nonlinear effects observed in laboratory experiments, and particularly the increase of strain amplitude leading to cyclic liquefaction of dense sand, are well captured by the elastoplastic model. Assessing the behaviour of granular soils under earthquake loadings clearly requires to take into account the nonlinear features of sand behaviour in terms of pore pressure generation and strain amplitude.