Stucky SA

Rue, Switzerland

Stucky SA

Rue, Switzerland
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Pachoud A.J.,Ecole Polytechnique Federale de Lausanne | Pachoud A.J.,Stucky SA | Manso P.A.,Ecole Polytechnique Federale de Lausanne | Schleiss A.J.,Ecole Polytechnique Federale de Lausanne
Engineering Fracture Mechanics | Year: 2017

When for steel liners of pressure tunnels and shafts high-strength steels are used, welded joints are subject to the risk of hydrogen induced cold-cracking in the base material. Longitudinal butt welded joints are critical regions as they are loaded transversely. For an accurate engineering fatigue and fracture assessment, solutions for stress intensity factors (SIF) are required, considering the weld shape and the global behavior of the liner (i.e., geometrical imperfections and interaction with surrounding concrete and rock). In this study, SIF for axial semi-elliptical surface cracks and embedded elliptical cracks at longitudinal butt welded joints of steel liners are studied by means of the finite element method. At first the applicability of published parametric equations for SIF of elliptical cracks in plates is validated. Then the influence of the weld shape is assessed through a systematic parametric study. It is shown that the weld profile has a significant influence on SIF for semi-elliptical surface cracks while it has no significant influence on SIF for embedded elliptical cracks within the studied range of relative crack depth. Finally, a new parametric equation is proposed to estimate the weld shape correction factor for semi-elliptical surface cracks. © 2017 Elsevier Ltd

Agency: European Commission | Branch: FP7 | Program: MC-ITN | Phase: FP7-PEOPLE-2013-ITN | Award Amount: 3.73M | Year: 2013

Sediment transport in the fluvial, estuarine and coastal environment causes significant morphological changes and results in the amplification of floods, storm surges and other inundation hazards. This increases considerably the risk of failure of structures, disruption of function of networks (water, energy), destruction of ecosystems and natural resources, as well as property and human loss. The impact of sediment transport is expected to be incremented due to climate change. Thus, it is very important to advance knowledge and train future engineers in this field. Herein we propose the formation of a Network for the training of young researchers in all application areas of sediment transport. The Network consists of six academic and four industrial partners and provides an elaborate and interdisciplinary training-through-research program to 12 early stage and 4 experienced researchers. It includes a comprehensive academic program, secondments at industrial partners, workshops, winter and summer schools, thematic conferences, production of guidelines and complementary activities. The proposed research focuses on: i) modeling and algorithm development for sediment transport in river and coastal flows and for inland and offshore turbidity currents or debris flows, and ii) experiments and simulations of sediment transport in river and coastal flows, and sediment-laden density underflows in reservoirs and submarine canyons. The experiments will allow for crucial phenomenological advances in the conceptual models upon which simulation tools are built. The latter, compatible with high performance computing, will be explored jointly by academic an industrial partners in real engineering applications during and after the duration of the project. This network is structured to help the coordination of research and educational activities in sediment transport in a European level and increase the European competitiveness in this important field of S&T.

Leite Ribeiro M.,Ecole Polytechnique Federale de Lausanne | Leite Ribeiro M.,Stucky SA | Blanckaert K.,Ecole Polytechnique Federale de Lausanne | Blanckaert K.,CAS Research Center for Eco Environmental Sciences | And 2 more authors.
Water Resources Research | Year: 2012

The hydromorphological implications of the local widening of a tributary where it enters a confluence were investigated in a laboratory setting that is representative of the 20 major confluences on the channelized Upper Rhone River. Although local tributary widening reduces the confluence angle, it amplifies the hydromorphosedimentary processes in the confluence hydrodynamic zone (CHZ), because local widening reduces the effective flow area, causing increased tributary velocities and momentum flux. The reduction in effective flow area is caused by an increase in bed elevation and by lateral constriction of the flow induced by flow stagnation at the upstream corner of the confluence. The increased tributary velocities amplify the two-layer flow structure in the CHZ. Flow originating from the tributary is confined to the upper part of the water column and is more markedly directed outward than flow in the lower part of the water column originating from the main channel. A shear layer characterized by increased turbulence activity develops at the interface between the two flow layers. The increased tributary velocities enhance bed discordance, the penetration of the tributary into the CHZ and the channel bed gradients in the postconfluence channel. The results indicate that local tributary widening can enhance heterogeneity in sediment substrate, flow velocities and flow depths. Widening may therefore enhance local habitat and improve the connectivity of the tributary to the main river network. This may, in turn, provide favorable conditions for the improvement and reestablishment of ecological river functions, without having adverse impact on flood safety. © 2012. American Geophysical Union. All Rights Reserved.

Leite Ribeiro M.,Stucky SA | Leite Ribeiro M.,Ecole Polytechnique Federale de Lausanne | Bieri M.,Ecole Polytechnique Federale de Lausanne | Boillat J.-L.,Ecole Polytechnique Federale de Lausanne | And 3 more authors.
Journal of Hydraulic Engineering | Year: 2012

In recent years, spillway rehabilitation has increased in importance and become the subject of many projects worldwide. One solution for this problem is the implementation of a new type of labyrinth spillway, called Piano Key Weir (PK-Weir ). This is an excellent alternative for increasing the overflow capacity of existing dams. Similarly to traditional labyrinth weirs, the hydraulic capacity of a PK-Weir is a function of its geometrical characteristics. Currently, there is a lack of systematic experiments, and the existing data does not allow the proposition of a universal design procedure. This paper reviews the previous studies on the efficiency of planned and built PK-Weirs. The results are evaluated by comparing an actual PK-Weir's discharge to that theoretically obtained for a sharp-crested spillway with crest length equal to the width of the PK-Weir for a given hydraulic head. On the basis of this evaluation, a preliminary design procedure is proposed. © 2012 American Society of Civil Engineers.

Leite Ribeiro M.,Stucky SA | Schleiss A.J.,Ecole Polytechnique Federale de Lausanne
Swiss Competences in River Engineering and Restoration - Special Session on Swiss Competences in River Engineering and Restoration of the 7th International Conf. on Fluvial Hydraulics, RIVER FLOW 2014 | Year: 2014

River channel confluences form important morphological components of any river system. This article presents the results of an investigation on a natural river confluence in Switzerland. The aim of the field work performed at the confluence of the Sarine (main channel) and Gerine (tributary) Rivers near Fribourg (CH) is to analyze the interaction between morphological processes on the confluence and hydropower-affected hydrology of the main River. Important morphological changes have been observed over the last years, especially the deflection of the Sarine River and erosion of the left bank opposite of the tributary. Numerical calculations have shown that currently the minimal discharge of the Sarine River which transports the sediments annually deposited at the confluence is attained on average once each 2 years. Before the construction of the Rossens Dam, the minimum discharge was reached every year. This lack of yearly floods with sediment mobilization can explain the morphological changes occurred at the confluence since the construction of the dam. © 2014 Taylor & Francis Group, London.

Ribeiro M.L.,Ecole Polytechnique Federale de Lausanne | Ribeiro M.L.,Stucky SA | Pfister M.,Ecole Polytechnique Federale de Lausanne | Schleiss A.J.,Ecole Polytechnique Federale de Lausanne | Boillat J.-L.,Ecole Polytechnique Federale de Lausanne
Journal of Hydraulic Research | Year: 2012

Piano Key Weirs (PKWs) are an alternative to linear overflow structures, increasing the unit discharge for similar heads and spillway widths. Thus, they allow to operate reservoirs with elevated supply levels, thereby providing additional storage volume. As they are relatively novel structures, few design criteria are available. Hence, physical model tests of prototypes are required. This study describes comprehensive model tests on a sectional set-up of several A-type PKWs, in which the relevant parameters were systematically varied. Considering data of former studies, a general design equation relating to the head-discharge ratio is derived and discussed. The latter is mainly a function of the approach flow head, the developed crest length, the inlet key height, and the transverse width. To extend its application range, case study model tests were analysed to provide a design approach if reservoir approach flow instead of channel flow is considered. © 2012 Copyright International Association for Hydro-Environment Engineering and Research.

Schleiss A.J.,Ecole Polytechnique Federale de Lausanne | Manso P.A.,Ecole Polytechnique Federale de Lausanne | Manso P.A.,STUCKY SA
Rock Mechanics and Rock Engineering | Year: 2012

Using high-strength steels for pressure shafts and tunnel liners and taking into account significant rock mass participation allows the design of comparatively thin steel liners in hydropower projects. Nevertheless, during emptying of waterways, these steel linings may be endangered by buckling. Compared with traditional measures such as increased steel liner thickness and stiffeners, pressure relief valves are a very economical solution for protection of steel liners against critical external pressure and therefore buckling during emptying. A calculation procedure has been developed for the design of the required number and arrangement of pressure relief valves, and this has been used successfully in practice. Systematic model tests enabled the assumptions of the design method to be verified. © 2011 Springer-Verlag.

Duarte R.,Ecole Polytechnique Federale de Lausanne | Ribeiro J.,Ecole Polytechnique Federale de Lausanne | Ribeiro J.,Stucky SA | Boillat J.,Ecole Polytechnique Federale de Lausanne | Schleiss A.,Ecole Polytechnique Federale de Lausanne
Journal of Hydraulic Engineering | Year: 2011

The overall dam-break phenomenon is currently well understood for reservoirs filled with water. However, many dams face serious problems of reservoir sedimentation. Thus, regarding risk management, the influence of a large amount of sediment in the reservoir on dam-break wave propagation is of great importance. Experimental investigations were performed to investigate the influence of the silting degree of reservoirs and grain size distribution on wave heights and velocities. Dam-break waves in silted-up reservoirs are the result of a two-phase flow formed by a layer of water over a layer of saturated sediments in which complex phenomena occur simultaneously. Sediments flow such as a viscous fluid from the dam breach until complete stoppage, and clear water flows over the sediments creating bed load transport. The final sediment deposition cone, the flow of the positive front, and maximum wave heights were studied. An empirical formula is proposed to describe the celerity of the positive wave front in the case of silted-up reservoirs. © 2011 American Society of Civil Engineers.

Canale L.,Stucky SA
International Journal on Hydropower and Dams | Year: 2013

During studies for the foundation treatment at the Nenskra rockfill dam in Georgia, an economic analysis was carried out, as part of the feasibility study, to weigh the losses associated with seepage against the cost of a deep cutoff wall. A partial cutoff solution was found to represent a good compromise, reducing costs while limiting seepage to an acceptable level.

Cekerevac C.,STUCKY SA | Wohnlich A.,STUCKY SA
Rock Mechanics in Civil and Environmental Engineering - Proceedings of the European Rock Mechanics Symposium, EUROCK 2010 | Year: 2010

The paper addresses the foundation stability analysis of two Swiss dams, namely Spitallamm arch-gravity dam (in the scope of a rehabilitation and heightening project) and lesToules arch dam (rehabilitation). The first example is actually in the design phase, with construction scheduled during the next decade, whilst the former one is currently under rehabilitation (2008-2011). The projects are reviewed with respect to the foundation stability conditions. The approach is similar in both cases: first the existing dam is back-analyzed, with emphasis on the foundation conditions, allowing the cross-checking of the design results with the available monitoring data (benchmarking). Based on that, the heightening and/or rehabilitation project is prepared and the most optimized solution in terms not only of safety but also of construction schedule and technology had been recommended. © 2010 Taylor & Francis Group.

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