Die Nutzung von Grundwasser zum Heizen und Kühlen ist nach den Erdwärmesonden die zweithäufigste Anwendung oberflächennaher oder untiefer Geothermie. Anders als bei den Erdwärmesonden haben die Änderung der Grundwassertemperatur und der Förderbetrieb relativ weiträumige Auswirkungen, welche oft weit über die Grundstücksgrenzen hinausreichen. Die begrenzten Ressourcen einerseits und der berechtigte Schutz des Grundwassers andererseits macht die Normierung seiner Nutzung erforderlich.
The extension of Grimsel 3 hydropower project (600 MW) entails the construction of a 2.5 km long tailrace tunnel, a machine and a transformer cavern as well as a new 600 m deep vertical shaft connecting the existing conduit with the Raterichsboden reservoir. Generally high in-situ stress conditions are expected for the construction of the extension of Grimsel 3 hydropower project within the massive Grimsel granodiorite and granite. Due to higher ground coverage for the cavern structure, brittle rock mass behaviour is expected influencing the constructionin the course of the relocation for the vertical shaft. The specific intact rock and rock mass conditions as well as the stress conditions were investigated by means of 600 m deep core drillings in order to obtain the geomechanical conditions and parameters at cavern structure level. The investigation included detailed analyses of brittle rock parameters as well as in-situ hydro-fracturing tests. Brittle parameters of rock were utilised for the two and three dimensional finite element analyses to determine the depth of spalling and fracturing expected for the construction. The variances of the two and three dimensional finite element analyses as well as the influence of brittle parameters influencing the analyses are discussed.
Hydropower plants are of great relevance for European energy production. Inclined or vertical shafts serve as a cost alternative to inclined steel-lined shafts in case of favourable ground conditions. Vertical shafts have a higher ground coverage compared to inclined shafts oriented parallel to the surface. The increased ground coverage and the resulting higher in-situ stress magnitudes may allow for unlined solutions instead of cost-intensive steel-lining. Depending on the strength and thickness of the concrete lining, unreinforced concrete tends to crack intensely upon exceeding a critical effective internal water pressure. The structural integrity is associated with the number of induced cracks and the crack width at a given internal water pressure. The design of the concrete lining depends on the bedding of the lining (e. g. deformability of the rock mass), the hydraulic conductivity of the rock mass in relation to the concrete lining, the external and internal water pressure, and the in-situ stress state. The paper presents a procedure to determine the stress state within a concrete lining and the surrounding rock mass.
AbstractAs the demand for electrical energy in Europe is constantly increasing, particularly at peak times, the pumped storage power station under construction at Nant de Drance in the canton of Valais has assumed a central position in the new Swiss energy policy. This power station represents an ideal means of storing large quantities of energy, which is generated more and more from wind and solar with their unreliable delivery dependent on meteorological conditions.This 900 MW project is mostly being constructed underground and fits optimally into an existing hydropower complex. A system of tunnels about 15 km long is being constructed for access to the plant, including the 5.5 km and 9.5 m diameter long main access tunnel, which is being driven by a tunnel boring machine. In parallel to the underground works, the Vieux Emosson dam is being raised by 20 m, which will double the storage capacity of the headwater reservoir.The core components of the plant are the six 150 MW vario‐speed Francis pump‐turbines, which will be housed in a machine cavern 184 m long, 52 m high and 32 m wide. Immediately next to the machine cavern are further caverns for the transformers and the gas‐insulated switchgear.The investment costs for the entire project are about 1.8 billion CHF plus interest. Construction works started in 2008 and the six pump‐turbines should start operation in stages in 2016 to 2018.In einer Zeit, in der der Bedarf an elektrischer Energie und insbesondere an Spitzenenergie stetig zunimmt, wird das im Bau befindliche Pumpspeicherkraftwerk Nant de Drance im Kanton Wallis zu einem zentralen Eckpfeiler der neuen schweizerischen Energiepolitik. Das Kraftwerk bildet ein ideales Mittel zur Speicherung von großen Energiemengen, welche mehr und mehr durch die relativ unzuverlässigen, von den meteorologischen Bedingungen abhängenden Quellen Wind und Sonne erzeugt werden.Dieses 900‐MW Projekt wird zu einem großen Teil unter Tage erstellt und fügt sich optimal in einen bereits bestehenden Wasserkraftwerkskomplex ein. Zur Erschließung der Anlage wird ein insgesamt rund 15 km langes Tunnel‐ und Stollensystem erstellt. Dazu gehört unter anderem ein 5.5 km langer Hauptzugangstunnel mit 9.5 m Durchmesser, der mittels Tunnelbohrmaschine vorgetrieben wird. Parallel zu den Tätigkeiten unter Tage wird die Staumauer Vieux Emosson um 20 m erhöht, wodurch die Speicherkapazität des oberen Stausees verdoppelt wird.Das Kernstück der Anlage bilden sechs 150 MW Vario‐Speed Francis‐Pumpturbinen, die in einer 184 m langen, 52 m hohen und 32 m breiten Maschinenkaverne untergebracht sind. Unmittelbar neben der Maschinenkaverne wird eine weitere Kaverne für die Maschinentransformatoren und die GIS‐Schaltanlage erstellt.Die Investitionskosten des gesamten Projektes belaufen sich auf rund 1.8 Mrd. CHF, Bauzinsen dazugerechnet. Die Bauarbeiten haben 2008 begonnen. In den Jahren 2016 bis 2018 sollen die sechs Pumpturbinen gestaffelt in Betrieb genommen werden.
