Center dEtudes des Tunnels

Bron, France

Center dEtudes des Tunnels

Bron, France
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Tran Manh H.,Center Detudes Des Tunnels | Tran Manh H.,University Paris Est Creteil | Sulem J.,University Paris Est Creteil | Subrin D.,Center Detudes Des Tunnels | Billaux D.,Itasca Consultants SA
Rock Mechanics and Rock Engineering | Year: 2015

Most of the viscoplastic models used to describe the constitutive behavior of squeezing grounds assume isotropic deformation. However, it is commonly observed that squeezing behavior is characterized not only by large time-dependent but also often by anisotropic deformations. This study uses a semi-empirical approach based on the analysis of convergence measurements and a numerical model that takes into account the time-dependent and the anisotropic response of the rock mass to investigate the squeezing behavior of the Saint-Martin-la-Porte access gallery, excavated within the Lyon–Turin railway project. We first show how the semi-empirical convergence law of Sulem et al. (Int J Rock Mech Min Sci Geomech Abstr 24(3):155–164, 1987a; Int J Rock Mech Min Sci Geomech Abstr 24(3):145–154, 1987b) can be extended to anisotropic tunnel closure by considering an elliptical deformation of the rock mass and by fitting the convergence data along the principal axes of deformation. A new anisotropic time-dependent constitutive model is then proposed. This model includes ubiquitous joints of specific orientation embedded in an isotropic viscoplastic medium. This model is implemented in FLAC3D and numerical simulations are performed to back-analyze the anisotropic closure of the Saint-Martin-la-Porte access gallery. An efficient two-step procedure for calibrating the model parameters is proposed: the parameters of the isotropic solid matrix are first estimated by performing axisymmetric numerical simulations. The parameters of the ubiquitous joints are then calibrated by performing 3D computations. It is shown that the numerical results reproduce very well the convergence measurements of the studied sections of Saint-Martin-la-Porte gallery. © 2015, Springer-Verlag Wien.

Vu T.M.,Center dEtudes des Tunnels | Vu T.M.,University Paris Est Creteil | Sulem J.,University Paris Est Creteil | Subrin D.,Center dEtudes des Tunnels | And 2 more authors.
Rock Mechanics and Rock Engineering | Year: 2013

In this paper, we analyse the convergence measurements recorded in a gallery excavated in severely squeezing ground. The procedure consists in a preliminary geometrical treatment of the raw data to evaluate the principal axes of deformation by assuming an elliptic deformation of the walls of the gallery. Then the convergence law proposed by Sulem et al. (Int J Rock Mech Min Sci Geomech Abstr 24(3):145-154, 1987a), which is extended to account for anisotropic closure, is fitted on the displacements along the two axes of the obtained ellipse. This procedure is more robust and relevant than fitting the convergence recorded on the most deforming segment or fitting the average value of the convergence along the various segments. An attempt is made to correlate the amount and the direction of anisotropic deformation with the lithology and some geological features described by the dominant discontinuity families. © 2012 Springer-Verlag Wien.

Vu T.M.,Center dEtudes des Tunnels | Vu T.M.,University Paris Est Creteil | Sulem J.,University Paris Est Creteil | Subrin D.,Center dEtudes des Tunnels | Monin N.,Lyon Turin Ferroviaire SAS
Rock Mechanics and Rock Engineering | Year: 2013

A semi-analytical solution based on the transfer matrix technique is proposed to analyze the stresses and displacements in a two-dimensional circular opening excavated in transversely isotropic formation with non-linear behavior. A non-isotropic far field can be accounted for and the process of excavation is simulated by progressive reduction of the internal radial stress. A hyperbolic stress-strain law is proposed to take into account the non-linear behavior of the rock. The model contains seven independent parameters corresponding to the five elastic constants of an elastic material with transverse isotropy and to the friction coefficient and cohesion along the parallel joints (weakness planes). This approach is based on the discretization of the space into concentric rings. It requires the establishment of elementary solutions corresponding to the stress and displacement fields inside each ring for given conditions at its boundaries. These solutions, based on complex variable theory, are obtained in the form of infinite series. The appropriate number of terms to be kept for acceptable approximation is discussed. This non-linear model is applied to back analyze the convergence measurements of Saint-Martin-la-Porte access gallery. Short-term and long-term ground parameters are evaluated. © 2012 Springer-Verlag.

Tran Manh H.,Center Detudes Des Tunnels | Tran Manh H.,University Paris Est Creteil | Sulem J.,University Paris Est Creteil | Subrin D.,Center Detudes Des Tunnels
Rock Mechanics and Rock Engineering | Year: 2014

Closed-form solutions are of great interest for quick and accurate evaluation of stresses and displacements around underground excavations. Based on complex variable theory and on the method of conformal mapping, closed-form solutions for stresses and displacements around deep tunnels with arbitrary cross section in a homogeneous, transversely isotropic and linear elastic ground with non-isotropic far-field stress conditions are developed. The results obtained with the proposed analytical solution are compared with those obtained with the numerical code FLAC3D for some usual shapes of tunnel openings. © 2014, Springer-Verlag Wien.

Kashef A.,National Research Council Canada | Viegas J.,National Laboratory for Civil Engineering | Mos A.,Center dEtudes des Tunnels | Harvey N.,Parsons Brinckerhoff
ASHRAE Transactions | Year: 2012

Design fires are an intrinsic part in designing tunnels for fires. They provide, quantitatively, the fire characteristics that are used to establish the sizing of equipment in tunnels and the scenarios to consider when developing emergency response plans. They are also used, indirectly, when considering the impact of fires on the structure. As such, design fires form the base input for emergency ventilation, evacuation, and structural design analyses. A design fire is generally defined in terms of heat release rate, and species output as functions of time. This paper summarizes efforts to develop a set of design fire curves as a useful tool for road tunnel fire risk assessment. The developed design fire curves include the following phases: (1) incubation phase, (2) growth phase, (3) fully-developed phase, and (4) decay phase. © 2012 ASHRAE.

Phan M.T.,University of Marne-la-Vallée | Meftah F.,Cergy-Pontoise University | Rigobert S.,Laboratoire Central des Ponts et Chaussees | Autuori P.,Bureau dEtude | And 2 more authors.
Procedia Engineering | Year: 2011

This paper presents a coupled thermo-hydro-mechanical (THM) model enriched with a buckling-type criterion for progressive spalling. In the first part of the paper, a general fully coupled multi-phase THM model describing the behaviour of concrete at moderate and high temperatures is presented. Then the spalling criterion and its numerical implementation in the framework of the finite element method are presented. Finally, a simple 1D numerical example will illustrate the effectiveness of the implemented numerical approach. © 2011 Published by Elsevier Ltd.

Tran-Manh H.,ParisTech National School of Bridges and Roads | Sulem J.,ParisTech National School of Bridges and Roads | Subrin D.,Center Detudes Des Tunnels
Acta Geotechnica | Year: 2016

Time-dependent response of deep tunnels is studied considering the progressive degradation of the mechanical properties of the rock mass. The constitutive model is based on a rock-aging law for the uniaxial strength of the rock and for the Young’s modulus. A semi-analytical solution is developed for the stresses and displacements around a deep circular tunnel taking into account the face advance. The evolution of the plastic and damage zones over time is determined. Numerical examples are presented for the case of Saint-Martin-La-Porte access adit in France of the Lyon–Turin Base Tunnel. The computed results which are compared with the field data in terms of the convergence of tunnel wall and of the displacements inside the rock mass monitored by multi-point extensometers show the efficiency of the approach to simulate the time-dependent deformation of a tunnel excavated in squeezing ground. Simple relationships are proposed to evaluate the parameters of the constitutive model directly from those of the empirical convergence law presented in previous work. © 2016 Springer-Verlag Berlin Heidelberg

Berthoz N.,Center Detudes Techniques Of Lequipement Mediterranee | Branque D.,National School of Public Civil Engineering | Wong H.,National School of Public Civil Engineering | Subrin D.,Center dEtudes des Tunnels
Canadian Geotechnical Journal | Year: 2013

The capacity of a commercially available miniature pressure sensor for measuring stress evolutions in a partially saturated soil under quasi-static loads is studied, in view of its later application in laboratory-scale physical models. An extensive calibration program is first performed on a triaxial cell under isotropic loadings. These calibration tests provide useful data for assessing the uncertainty in stress measurements, especially in the case of partially saturated granular materials. Notably, influences of soil density, water content, and average grain size on stress measurements are quantified. Following these tests, an example of stress measurements on an original reduced-scale model of "earth pressure balance shield" (EPBS) is presented, which involves three-dimensional arching effects developing around the shield during excavation.

Panigoni T.,Center dEtudes des Tunnels | Peru Y.,Center dEtudes des Tunnels
Rock Dynamics and Applications - State of the Art: Proceedings of the 1st International Conference on Rock Dynamics and Applications, RocDyn-1 2013 | Year: 2013

The major renovation works of the Croix-Rousse tunnel are located in a very urbanized district of Lyon between the Rhône and Saône rivers. The new tunnel was excavated mostly through granite and very hard gneiss formations. The rock quality, the limited work area and the tight construction schedule only allowed for an excavation method with explosives. This paper deals with the control of vibrations caused by blasting and the compliance with contractual specifications. The subject is sensitive since the works take place in a densely urbanized environment, very near to the existing tunnel which must be maintained full time under operation, except short traffic stoppages during blasting. © 2013 Taylor & Francis Group.

Taillefer N.,French Scientific and Technical Center for Building | Carlotti P.,French Scientific and Technical Center for Building | Larive C.,Center dEtudes des Tunnels | Lemerle C.,French Scientific and Technical Center for Building | And 2 more authors.
Fire Technology | Year: 2013

This paper recalls the genesis of the increased hydrocarbon temperature curve (HCinc) 10 years after its introduction in France. The statutory context, the role of the HCinc curve and the main issues raised are described. In the second section, results from fire resistance tests on concrete slabs exposed to the temperature curve in the framework of experimental research programs are presented and discussed. They are supplemented by a summary of a large number of commercial tests. An original test protocol allowing subjecting the slabs heated surface in compression is described. In the last section, current trends for fire resistance design in France are given. Assessment methodology for new and existing tunnels based on experiments and simulation are described. Recommendations are finally given in the utilization of passive protections. © 2012 Springer Science+Business Media, LLC.

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