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Jeannin, P. - Y. (2015). KARSYS, KarstALEA, la spéléologie et le canton de Neuchâtel. Cavernes, .
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Jeannin, P. - Y. (2007). La problématique du karst lors du creusement d'un tunnel. Bull. Angew. Geol, 12/2, 27–38.
Résumé: Après une introduction décrivant les problèmes de génie civil en milieu karstique, cet article présente un aperçu des caractéristiques principales de ce milieu. Un bref aperçu des formes karstiques typiques (dolines, ouvalas, lapiés, etc.) est suivi d�un petit chapitre résumant les particularités hydrologiques des massifs karstiques: 1) épikarst stockant et répartissant les infiltrations entre un écoulement rapide (conduits) et lent (volumes de roche fissurés et peu perméables); 2) zone non saturée atteignant souvent plusieurs centaines de mètres d�épaisseur; 3) zone épinoyée présentant des mises en charge de plusieurs centaines de mètres et 4) zone noyée renfermant un volume d�eau parfois considérable. Suit un chapitre sur la genèse et l�âge des formes karstiques, en particulier des conduits souterrains (grottes). La relation avec les gradients hydrauliques et la possibilité de développer des conduits en quelques centaines, voire dizaines d�années lorsque les gradients sont élevés (a proximité de tunnels ou de barrages) y est relevée. La deuxième partie de l�article présente les recherches en cours pour prévoir la position des conduits karstiques dans les massifs, ce qui est particulièrement intéressant lors du creusement de tunnels. Il apparaît que les conduits se développent préférentiellement le long d�horizons géologiques particuliers (horizons d�inception) que l�on doit pouvoir reconnaître sur le terrain. La prévision de la position des conduits karstiques s�en trouve nettement améliorée.
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Jeannin, P. - Y., Malard, A., Rickerl, D., & Weber, E. (2015). Assessing karst-hydraulic hazards in tunneling – the Brunnmühle spring system – Bernese Jura, Switzerland. Environmental Earth Sciences, 74(12), 7655–7670.
Résumé: Drilling a tunnel in a karst region requires the assessment of disturbances in the
hydrogeological functioning of aquifers and flow-systems as well as disturbances for
the tunnel itself. A complete characterization of the karst hydrogeological functioning
and the establishment of prevention measures are essential in order to insure a
suitable construction. The paper relates investigations which were conducted in the
frame of the construction of a safety gallery (Sisto) in the bernese Jura (Switzerland).
This gallery is located close to the outlet of a regional karst system and parallel to an
existing highway tunnel, which met numerous disorders in the past due to the
intersection of active karst conduits with a discharge reate exceeding 1 m3/s.
The KarstALEA method was applied along the Sisto trace in order to identify sections
with a high probability of karst occurrences and to characterize the type of karst related
problems. The main issue turned out to be related to water head and discharge, which
could potentially be cut by the tunnel construction. The system discharge rate may
frequently exceed 10 m3/s, and most of this water could potentially flow into the tunnel.
Therefore, a hydraulic model was set up in order to assess expected flow rates and
heads if conduits are intersected during the construction. Based on this model and on
meteorological and hydrological real-time measurements, a predictive model was
established in order to anticipate high-flows events.
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Malard, A., Jeannin, P. - Y., & Rickerl, D. (2015). Impact of a Tunnel on a Karst Aquifer: Application on the Brunnmühle Springs (Bernese Jura,Switzerland). In Hydrogeological and environmental investigations in karst systems. Environmental Earth Sciences (pp. 457–463). Springer.
Résumé: Tunnel drilling in karst regions often leads to major disturbances in the hydrogeological functioning of
aquifers and flow-systems. Numerous examples in Switzerland do exist and induced significant costs,
which were not or rarely anticipated (e.g.: Flims, Jeannin et al. 2009). The Ligerztunnel is one such
example. The tunnel was built a few hundreds of meters upstream from the Brunnmühle spring, which
contributes to the drinking water supply of communities of Twann and Ligerz. During the construction, a
major karst conduit with a huge discharge rate was intersected in a side exploration tunnel. Overflowing
water was diverted in the Twannbach canyon. In the main section, smaller conduits were found and
drained outside by pipe leading water close to the Brunnmühle spring. Actually, authorities want to add a
safety gallery parallel to the main tunnel. In this view, SISKA is in charge of evaluating the hydrological
disturbances on the spring regime. The paper presents the approach applied to assess the potential effect of
the drilling of a new tunnel near to a group of karst springs and pumping wells. The approach combines
available spatial information and a hydraulic model. The KARSYS approach is first applied on the system
in order to set up a 3D geological and hydrogeological model of the karst aquifer and the related systems.
The spatial distribution of karst conduits within the massif is assessed based on a speleogenetical and
inception horizons model (KarstALEA method). Inferring from these models, a karst conduits network is
generated. The downstream part of the conduits network, which concerns the vicinity of the tunnels
project, is precisely calibrated using head and discharge data. Flow in this conduits network is then
simulated using SWMM 5.0 in order to reproduce the hydrological responses of the different outlets
(permanent springs, drainage devices, overflow springs, etc.).
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McCormack, T., Vouillamoz, J., Gil, L. W., & Lee, M. (2015). Modelling Inception Horizons and their Influence on Groundwater Flow Pathways in a Karstic Catchment. In Geoscience 2015, Dublin, November 2015, Poster.
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