L. Tacher

• Swiss Federal Institute of Technology in Lausanne

Prediction of hydraulic perturbations induced by the construction and the operation of deep geological radioactive waste repository is need to support: (i) the engineering and monitoring operations, and (ii) the assessment of the consequences on groundwater resources. Andra (French National Radioactive Waste Management Agency) has developed a three...

This study aims to evaluate the hydraulic impacts of the construction of a deep geological radwaste repository planned by the ANDRA (French National Agency for Nuclear Waste Management) within the Meuse aquifer system in the east of the Paris basin. A three-dimensional numerical model of variably-saturated flow was developed with respect to the con...

The French National Agency for Nuclear Waste Management (Andra) conducted a site investigations program within the project of a deep geological disposal of intermediate and high-level long lived radioactive waste in the Meuse/Haute-Marne region. The construction of the shafts to the underground Laboratory in the Callovo-Oxfordian clay host formatio...

This study describes transient hydrogeological and geomechanical models realized jointly in 2006 by the Geolep office (Géologie de l’Ecole Polytechnique) of the Polytechnical School of Lausanne (EPFL) and GeoMod SA within the framework of the stabilization work of the La Frasse landslide (Vaud, Switzerland). These models evaluate the impact of a de...

During a series of environmental analysis carried out in soil and groundwater in the Alpine Valley (Rhone valley Western Switzerland), were identified high levels of chlorinated solvents, particularly the tetrachloroethene. The leakage of this pollutant originates from industry. The geological substratum in this part of the valley is mainly compose...

Recent studies on the complex 3D geometry of large cave systems around the World allowed us to get statistical evidence of the inception horizon hypothesis. It clearly confirmed the idea that the development of karst conduits under phreatic conditions is strongly related to a restricted number of so called inception horizons. An inception horizon i...

It is well known that the most important triggering mechanism for rapid landslides is the infiltration of precipitation water at the surface of slopes which decreases the soils shear strength. However, the present study put focus on the exfiltration of groundwater from the substratum and its effect on the triggering of overlying landslides. Which i...

Using advanced hydrogeological and geomechanical finite element modelling, it has been possible to model the mechanical behaviour of a large slope movement, the Triesenberg landslide. This slope is located along the Rhine valley in the Principality of Liechtenstein, covering an area of around 5 km2 which includes two villages. Pore water pressure f...

This paper outlines the conclusion from an analysis of 18 large cave systems around the world, comprising more than 1500 km of conduits. The 3D geometry of complex cave systems have been analysed in relation to their geological context as well as their hydrogeological boundary conditions. The methodology allowed for the first time statistical evide...

Implantation and use of shallow geothermal systems may have environmental impacts. Traditionally, risks are divided into 2 categories: direct and indirect. Direct risks are linked with the leakage of the circulating fluid (usually water with anti-freeze) of ground source heat pumps into the underground which may be a source of contamination. Indire...

To assess hill slope stability and landslide triggering mechanisms, it is essential to understand the hydrogeological regime in slopes. In this work finite element models are elaborated and field experiments are carried out to study particularly shallow landslides with thickness of a few meters. The basis hypothesis of the presented research assume...

The consideration of predicted climate change conditions in the hydrogeological and geomechanical modelling of a large landslide allows the assessment of its future behaviour in case of crisis. This application shows that the predictions are not necessarily pessimistic, despite of the uncertainties of the needed assumptions.

The urban underground is the reservoir of four main resources, space groundwater, geothermal energy and geomaterials. Their exploitation have until now essentially followed a sectorial approach. It has often resulted in conflicts of uses and waste of resources. This situation could have been avoided by the development of a more global planning stra...

The project "Underground resources and sustainable development in urban areas" (called also "Deep City Project") is motivated by the critical congestion of many cities around the world leading to environmental and public health problems. Consequently, it is obvious that major changes are needed in order to reach new conditions, which are more compa...

The smoothed particle hydrodynamics (SPH) method is extended and tested for the numerical simulation of transient viscoelastic free surface flows. The basic equations governing the free surface flow of an Oldroyd-B fluid are considered and approximated by SPH. In particular, a drop of an Oldroyd-B fluid impacting a rigid plate is simulated. Results...

Subsurface models are generally built from both subjective interpretation and mathematical interpolation/extrapolation techniques. These models are therefore uncertain, but their uncertainty is rarely expressed in a geological forecast. In this paper, an evaluation method of geological uncertainties related to 3-D subsurface models is proposed and...

This study proposes a general methodology, applied in Switzerland, for the delineation of protection areas for abstracted groundwater against persistent chemical contaminants in order to establish: (1) remediation programmes in the event of contamination and (2) prevention programmes, in a general way. This new approach is based on the complete gro...

This paper describes the solution of the backward-type Kolmogorov equation (backward method) as an alternative to the forward method to determine the probability (P) of a trace particle reaching a given region within a time tau, which is of interest in groundwater contamination investigation, such as pollution monitoring and controlling. The backwa...

The alpine valley of the Haute-Sarine is on several accounts representative of the alluvial aquifers of mountain by its very environment and its hydrogeologic characteristics. The investigations and the analysis carried out within the framework of this study enabled us to improve knowledge on the Quaternary filling of the valley and to highlight th...

Thanks to a sophisticated transient hydrogeological modelling allowing the determination of the pore pressure fields in La Frasse landslide mass during a crisis, it has been possible to model the mechanical behaviour of the slide and obtain results that prove to be similar to the monitored data, in terms of peak velocity, distribution of velocity w...

Within a large multidisciplinary project, a well-structured and interactive knowledge database was developed aimed at providing MS and PhD students with a comprehensive and well-illustrated information on all natural hazards and risks. In particular it develops methods to plan investigation works and interpret landslide field data and monitoring re...

Vertical growth of cities into the ground is still to be developed, in particular for transport, storage of goods and geothermal exploitation. This article presents a synthesis of the potential resources offered by the urban underground and some experiences derived from different cities around the world. Analysis of these experiences shows that the...

This paper presents a new computer algorithm for generating spatially-correlated random fields. Such fields are often encountered in hydrology and hydrogeology and in the earth sciences and used as inputs for Monte Carlo simulations. The algorithm is designed by using a multilevel grid strategy and combining the matrix decomposition (MD) method and...

The use of hydrothermal simulation models to improve the prediction of water inflows in underground works during drilling is tested in the Mont Blanc tunnel, French and Italian Alps. The negative thermal anomaly that was observed during the drilling of this tunnel in 1960 is reproduced by long-term, transient hydrothermal simulations. Sensitivity a...

Durante la campaña oceanográfica BIG ‘95, desarrollada en aguas del Mar Catalano-Balear a bordo del B.I.O. Hespérides en Mayo de 1995, se cartografió, a partir de los datos batimétricos obtenidos con la sonda multihaz SIMRAD EM-12S, un área de 12.360 km2 en la parte distal del margen continental del Ebro. En la zona se han identificado 5 canales tu...

A discrete reduced distance method to generate 2-D and 3-D granular porous media is presented. The main property of the method is to produce heterogeneous and/or anisotropic packed beds of joined grains with arbitrary shapes and optimum fitting (i.e., minimum porosity). The iterative generation process starts with the coarsest grain and adjusts the...

Engineers and geologists have two different points of view concerning the interaction between groundwater and underground works. The former considered the impact of water on underground works in terms of technical effects while the latter study the incidence of the works on groundwater resources. In fact, these two aspects cannot be separated: they...

Finite element generation methods, such as Delaunay, allow the meshing of shapes from a set of nodes. These nodes must previously exist. The authors present a simple, fast and reliable method to generate them in an unstructured way in N-dimensional space. Its main characteristic is to easily allow variation of the node density by introducing a dens...

What is the potential of city's geological underground for its sustainable development? The project "Underground resources and sustainable development in urban areas" (called also "Deep City Project") is motivated by the critical congestion of many cities around the world leading to environmental and public health problems. Consequently, it is obvi...

The horizontal expansion and increase in population that have characterised urban growth and development patterns of the last few decades have produced cities that are often inconsistent with the principles of sustainable development. Due to the high rate of global urbanisation, problems such as greater traffic congestion, higher levels of air poll...

3rd interim report, European Spatial Planning Observation Network (ESPON) project 1.3.1

research report 2004, Glissement de la Frasse, plus annexes

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