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Mönchaltorf, Switzerland

Kim H.-M.,Korea Institute of Geoscience and Mineral Resources | Lettry Y.,Solexperts AG | Park D.,Korea Institute of Geoscience and Mineral Resources | Ryu D.-W.,Korea Institute of Geoscience and Mineral Resources | And 2 more authors.
Engineering Geology | Year: 2012

In this paper, we introduce a novel in-situ permeability measurement system and present the results of field permeability testing using the developed system. Using a modular structural design and wide measurement range from low to high permeability, the developed system was capable of measuring in-situ scale permeabilities of concrete linings, construction joints and rock mass around excavated rock caverns. Such measurements have been extremely limited so far but are essentially required in estimating the sealing performance of underground storage caverns. The experimental results of a concrete block model test as well as field permeability measurements of concrete linings and the excavation damaged zone (EDZ) around a lined rock cavern (LRC) in a pilot plant for underground compressed air energy storage (CAES) were presented. From these experimental measurements, we could verify the effective applicability of the developed system to a wide range of measurement conditions, from the low permeability concrete lining matrix to the highly permeable construction joints and fractured rock masses around underground rock storage caverns. © 2012 Elsevier B.V. Source

Wechner S.,Hydroisotop GmbH | Lettry Y.,Solexperts AG | Lerouge C.,Bureau de Recherches Geologiques et Minieres | Fernandez A.M.,CIEMAT | And 6 more authors.
Geological Society Special Publication | Year: 2014

Hydrogen gas was injected, together with helium and neon, into a borehole in the low-diffusivity Opalinus Clay rock. The hydrogen partial pressure was at most 60 mbar. A water production flow rate from the surrounding rock of c. 15 ml/day had been obtained previously, indicating that the test interval wall was presumably saturated with water. Helium and neon concentrations decreased as expected while taking into account dissolution and diffusion processes in the porewater. In contrast, the disappearance rate of hydrogen observed (2 × 10-4 to 3 × 10-4 mol/day/m2) was c. 20 times larger than the calculated rate considering only dissolution and diffusion. The same rate was observed following a new hydrogen injection and over a six-month semi-continuous injection phase. Simultaneously, sulphate and iron concentrations decreased in the water, whereas sulphide became detectable. These evolutions may be due to biotic processes involving hydrogen oxidation, sulphate reduction and Fe(III) reduction. © The Geological Society of London 2014. Source

Kim H.-M.,Sejong University | Lettry Y.,Solexperts AG | Ryu D.-W.,Korea Institute of Geoscience and Mineral Resources | Song W.-K.,Korea Institute of Geoscience and Mineral Resources
Materials and Structures/Materiaux et Constructions | Year: 2014

Concrete permeability is subject to various test conditions, and on-site measurement at in situ structural scale is much preferable. This paper presents an experimental study to measure the permeability of concrete linings and their construction (placing) joints between old and new concretes using a novel in situ permeability testing system. Using the developed system, we performed in situ scale permeability tests of rectangular concrete specimens with dimensions of 500 × 500 × 2800 mm3, within which the construction joints were artificially placed. From this model experiment, we verified an effective applicability of the system to both low permeability concrete matrices and highly permeable construction joints thanks to its selective capability of gas or water permeability test, depending on the air/water tightness of tested materials. The experimental results presented in this paper also showed that the intrinsic permeability of the construction joint could be higher than that of the concrete matrices by orders of magnitude (101-104 times), but it could be reduced to as low as those of the concrete matrix by pasting a bonding agent on the interfacing surfaces. As a result of geomechanical monitoring during the experiment, the opening displacement of construction joints with relatively higher stiffness values showed a reversible deformation when the gas injection pressure was unloaded, which is much preferable in a storage performance perspective of underground lined rock caverns. © 2013 RILEM. Source

Rocks containing clay and anhydrite exhibit the property of increasing their volume by absorbing water. The paper first discusses the mechanisms causing swelling and outlines their effects on tunnels. Next the hazard scenario of heaving of the tunnel tube as a whole, the structural consequences of this and the concept of the Modular Yielding System for tunnelling in stretches where heave is unavoidable are discussed. Taking the case of the Chienberg road tunnel in Switzerland, the paper also reports on experience during construction and field measurements after putting the repaired sections into operation. Special attention is given to the technical aspects of yielding supports with cement as a basic constituent for loads up to 10 MN and a yielding capacity of up to 50%. © 2010 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin. Source

Kech M.,Solexperts AG | Naterop D.,Solexperts AG | Senti R.,Nordostschweizerische Kraftwerke AG NOK
Rock Engineering in Difficult Ground Conditions - Soft Rocks and Karst - Proceedings of the Regional Symposium of the International Society for Rock Mechanics, EUROCK 2009 | Year: 2010

In-situ investigations were carried out for large power house caverns of the future pump storage power station Linth-Limmern, Canton Glarus, Switzerland. To investigate the bedrock at the cavern locations 10 horizontal to upward vertical inclined 50-130 m deep boreholes were drilled from an exploration tunnel and from two cross cuts. Many hydraulic and geotechnical borehole tests were performed. To estimate the hydraulic permeability in upwardly inclined boreholes two custom-made four-fold groundwater multi-level test systems were designed and built. These systems allow boreholes to be saturated so that hydraulic heads of the isolated borehole sections could be monitored and tested. The systems proved to be time- and cost-effective. The preferred in-situ testing provided site specific hydraulic and rock mechanical properties that were an essential element for design, tender and future construction of the caverns. © 2010 Taylor & Francis Group, London. Source

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