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Innertkirchen, Switzerland

Wannenmacher H.,Amberg Engineering Ltd. | Stucki A.,AF Consult Switzerland AG | Bauert M.,Amberg Engineering Ltd. | Ruegg C.,Amberg Engineering Ltd. | Schwegler B.,Kraftwerke Oberhasli AG KWO
Underground - The Way to the Future: Proceedings of the World Tunnel Congress, WTC 2013 | Year: 2013

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 costintensive 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. © 2013 Taylor & Francis Group.

Bieri M.,Ecole Polytechnique Federale de Lausanne | Schleiss A.J.,Ecole Polytechnique Federale de Lausanne | Jordan F.,E dric.ch Ingenieurs Conseils | Fankhauser A.U.,Kraftwerke Oberhasli AG KWO | Ursin M.H.,Kraftwerke Oberhasli AG KWO
Dams and Reservoirs under Changing Challenges - Proceedings of the International Symposium on Dams and Reservoirs under Changing Challenges - 79 Annual Meeting of ICOLD, Swiss Committee on Dams | Year: 2011

The simulation of run-off in alpine catchment areas is an important issue for the optimal operation of hydropower plants for normal flow conditions, but also during flood events. A semi-lumped numerical approach combines hydrological modelling and operation of hydraulic elements. It allows simulation of operating mode of complex storage hydropower plants and its impacts on the downstream river system for different scenarios. The modelling of the upper Aare catchment with the Oberhasli hydropower scheme in Switzerland is presented. The effect of the existing reservoirs and their management, taking into account preventive turbining, on flood routing in the Aare River upstream of Lake Brienz is presented for the 2005 and 1987 flood events. The enhancement project KWOplus, which contains a considerable increase of storage volume in the main reservoir as well as in turbining capacity, is estimated. © 2011 Taylor & Francis Group.

Moller G.,ETH Zurich | Boes R.M.,ETH Zurich | Theiner D.,Kraftwerke Oberhasli AG KWO | Fankhauser A.,Kraftwerke Oberhasli AG KWO | And 3 more authors.
Dams and Reservoirs under Changing Challenges - Proceedings of the International Symposium on Dams and Reservoirs under Changing Challenges - 79 Annual Meeting of ICOLD, Swiss Committee on Dams | Year: 2011

The Swiss utility Kraftwerke Oberhasli AG (KWO) currently implements "KWO plus", an upgrading program involving a large number of economical and ecological improvements of their hydropower schemes. A major project, the modification of the Handeck 2 power plant intake, requires total emptying of the Räterichsboden reservoir having an active volume of 25 million m 3. In order to define the most efficient and ecological emptying process for these circumstances, KWO commissioned a hybrid modelling program of the sediment remobilisation processes during the planned reservoir drawdown. Hydraulic model tests were conducted at the Laboratory of Hydraulics, Hydrology and Glaciology (VAW) by means of a 1:35 scaled Froude model. Numerical simulations of sediment transport were performed by the Laboratory of Hydraulic Constructions (LCH) using the software FLOW-3D. A good agreement between both models was found for total values of the sediment concentration and its variation in time. Both the physical and the numerical model were validated by prototype data obtained during an annual functional test of the bottom outlet. These measurements were conducted at three downstream positions in the Aare River. The involved solution procedures provide the (1) sediment flux during pressure flushing, (2) influence of outlet gate opening height and opening velocity on sediment concentration, and (3) time-dependent distribution of sediment concentration along the Aare River. © 2011 Taylor & Francis Group.

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