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Le Touquet – Paris-Plage, France

Calon N.,SNCF | Robinet A.,SNCF | Trinh V.N.,Systra
Civil-Comp Proceedings

The aim of this paper is to show the evolution of the trackbed design of railway platforms from the 19th century to the present. In France, there are more than 30,000 kilometers of operational classic lines in use and 2,000 kilometers of high speed lines (HSL). Initially, the classic lines were built without standards and the platform appeared by interpenetration of ballast and subgrade, creating an intermediate layer. For their part, the HSL are built according to standards defining the mechanical characteristics of the products used and the thickness of the layers. In this paper, first the difference between classical lines and HSL design are describe. Then the main developments, for new lines, in term of design (diminution of thickness of the layers) and products (utilization of treated materials) and for the track bed investigations on the old lines, are presented. Finally the paper focuses on the impact of those developments on track maintenance. © Civil-Comp Press, 2014. Source

Janin J.P.,University Paris Est Creteil | Martin A.,University Paris Est Creteil | Gastebled O.,Systra
Numerical Methods in Geotechnical Engineering - Proceedings of the 8th European Conference on Numerical Methods in Geotechnical Engineering, NUMGE 2014

In the current practice of underground project design, two-dimensional numerical modelling is usually sufficient. Nevertheless, a three-dimensional approach might be necessary in some cases to optimize and verify the geometry and the construction methods, especially for underground works to be excavated under tight constraints in urban environment. This study presents the case of aTBM dismantling cavern which is to be constructed for the future extension of a metro line in Paris, under sensitive residential buildings. At first, a 2D finite element model was used to assess the settlements caused by the excavation of a relatively long cavern. This first approach resulted in settlement predictions exceeding admissible thresholds. As a consequence, the size and the shape of the cavern as well as the excavation process were adapted. The validation of the design with respect to settlement control could finally be achieved using 3D modeling approach. © 2014 Taylor & Francis Group, London. Source

Patrizi P.,Systra
Geotechnical Aspects of Underground Construction in Soft Ground - Proceedings of the 7th International Symposium on Geotechnical Aspects of Underground Construction in Soft Ground

A consortium of major French contractors is currently realizing the works for Line 3 of the Underground of Cairo (Cairo is the first African city to have an Underground, back in the eighties). The line is divided into 4 phases, phase 1 (4.2 km) under construction, phase 2 (6.5 km) works to start soon, phase 3 (16.6 km) under design and phase 4 (12 km) still to be designed. This 40 km new line will connect western Cairo (left bank of the river Nile) to Cairo Business District on the right bank downtown and Cairo Airport on the east of the city. Ground conditions are made by a layer of clay/silt (up to 10 m) overlying a sandy silt layer and sand from 20 m up to 90 m and more. Ground water table is a couple of meters below street level. 1 km before the end of phase 1 a major collapse occurred in the slurry TBM, whose causes are yet to be understood. TBM recovery is being carried out through a shaft that is being excavated 3 m in front of the collapse point. Its diaphragm walls have been driven DOWN to a clay layer underlying the sand level to guarantee for watertightness (over 90 m panel depth). Ground freezing is then carried out to reach the shield, that is going to be extracted from the shaft, allowing the tunnel lining to be completed. The remaining tunnel of phase 1, as well as the beginning of phase 2 and the whole of phase 3 are going to be excavated with a new slurry machine that is expected to arrive to Cairo to complete the works. © 2012 Taylor & Francis Group. Source

Barla G.,Polytechnic University of Turin | Bonini M.,Polytechnic University of Turin | Semeraro M.,Systra
Tunnelling and Underground Space Technology

Recent innovations in yield-control support systems allow to increase the rate of advance when tunnelling in difficult conditions is associated with severely squeezing rock. Such systems which imply the insertion in the lining of highly deformable concrete elements are being adopted successfully in tunnelling projects using conventional excavation methods. The Saint Martin access adit excavated in a Carboniferous Formation along the Base Tunnel of the Lyon-Turin rail line is presented as a case study. Numerical analyses are discussed to compare the results of computed and measured performance of a typical monitored section and to find out possible optimizations of the support system adopted. © 2010 Elsevier Ltd. Source

Cheetham M.,Systems and Engineering | Mallet T.,Symadrem | Chastel E.,Symadrem | Tourment R.,IRSTEA | And 2 more authors.
Proceedings of the Institution of Civil Engineers: Water Management

The River Rhône in the south of France is susceptible to periodic flooding, leaving communities and vast areas of agricultural land inundated for significant periods of time. Efforts to control flooding in the lower Rhône valley have been undertaken since the middle of the nineteenth century, notably through the construction of levees and other flood defence and river management structures. These have subsequently been raised and widened following each major flood event, making their capacity to resist floods difficult to evaluate. Recent flood events have resulted in numerous breaches in the existing system of protection. The recent introduction of a global strategy for flood management in the lower Rhône catchment (Plan Rhône) includes for major infrastructure improvements to enhance the resilience of existing flood defences. This paper examines the application of the Plan Rhône since its release, presenting case studies and, where appropriate, the collaborative work undertaken by the main actors involved. This paper examines the application of the Plan Rhône since its release, presenting case studies and, where appropriate, the collaborative work undertaken by the main actors involved. Details of the different approaches undertaken to evaluate the risks associated with the levees are provided, together with proposed solutions to enhance the resilience of the global system of protection against a flood with a probability of exceedance of 1023 (1 in 1000 year return period). © ICE Publishing: All rights reserved. Source

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