Documents disponibles écrits par cet auteur

Face stability analysis of circular tunnels driven by a pressurized shield / Guilhem Mollon in Journal of geotechnical and geoenvironmental engineering, Vol. 136 N° 1 (Janvier 2010) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 1 (Janvier 2010) . - pp. 215-229 Titre : Face stability analysis of circular tunnels driven by a pressurized shield Type de document : texte imprimé Auteurs : Guilhem Mollon, Auteur ; Daniel Dias, Auteur ; Abdul-Hamid Soubra, Auteur Article en page(s) : pp. 215-229 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Tunnel  Limit  analysis  Tunnel  face  stability  Pressurized  shield  Upper-bound  method Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : The aim of this paper is to determine the face collapse pressure of a circular tunnel driven by a pressurized shield. The analysis is performed in the framework of the kinematical approach of limit analysis theory. It is based on a translational three-dimensional multiblock failure mechanism. The present failure mechanism has a significant advantage with respect to the existing limit analysis mechanisms developed in the case of a frictional soil: it takes into account the entire circular tunnel face and not only an inscribed ellipse to this circular area. This was made possible by the use of a spatial discretization technique. Hence, the three-dimensional failure surface was generated “point by point” instead of simple use of existing standard geometric shapes such as cones or cylinders. The numerical results have shown that a multiblock mechanism composed of three blocks is a good compromise between computation time and results accuracy. The present method significantly improves the best available solutions of the collapse pressure given by other kinematical approaches. Design charts are given in the case of a frictional and cohesive soil for practical use in geotechnical engineering. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&ONLINE=YES&s [...] [article] Face stability analysis of circular tunnels driven by a pressurized shield [texte imprimé] / Guilhem Mollon, Auteur ; Daniel Dias, Auteur ; Abdul-Hamid Soubra, Auteur . - pp. 215-229. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 1 (Janvier 2010) . - pp. 215-229 Mots-clés : Tunnel  Limit  analysis  Tunnel  face  stability  Pressurized  shield  Upper-bound  method Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : The aim of this paper is to determine the face collapse pressure of a circular tunnel driven by a pressurized shield. The analysis is performed in the framework of the kinematical approach of limit analysis theory. It is based on a translational three-dimensional multiblock failure mechanism. The present failure mechanism has a significant advantage with respect to the existing limit analysis mechanisms developed in the case of a frictional soil: it takes into account the entire circular tunnel face and not only an inscribed ellipse to this circular area. This was made possible by the use of a spatial discretization technique. Hence, the three-dimensional failure surface was generated “point by point” instead of simple use of existing standard geometric shapes such as cones or cylinders. The numerical results have shown that a multiblock mechanism composed of three blocks is a good compromise between computation time and results accuracy. The present method significantly improves the best available solutions of the collapse pressure given by other kinematical approaches. Design charts are given in the case of a frictional and cohesive soil for practical use in geotechnical engineering. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&ONLINE=YES&s [...]

Probabilistic analysis of circular tunnels in homogeneous soil using response surface methodology / Guilhem Mollon in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 9 (Septembre 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 9 (Septembre 2009) . - pp. 1314–1325 Titre : Probabilistic analysis of circular tunnels in homogeneous soil using response surface methodology Type de document : texte imprimé Auteurs : Guilhem Mollon, Auteur ; Daniel Dias, Auteur ; Abdul-Hamid Soubra, Auteur Année de publication : 2009 Article en page(s) : pp. 1314–1325 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : ShieldsTunnelingSettlementServiceabilityUltimate  loadsLimit  statesSystem  reliability Résumé : A probabilistic analysis of a shallow circular tunnel driven by a pressurized shield in a frictional and/or cohesive soil is presented. Both the ultimate limit state (ULS) and serviceability limit state (SLS) are considered in the analysis. Two deterministic models based on numerical simulations are used. The first one computes the tunnel collapse pressure and the second one calculates the maximal settlement due to the applied face pressure. The response surface methodology is utilized for the assessment of the Hasofer-Lind reliability index for both limit states. Only the soil shear strength parameters are considered as random variables while studying the ULS. However, for the SLS, both the shear strength parameters and Young’s modulus of the soil are considered as random variables. For ULS, the assumption of uncorrelated variables was found conservative in comparison to the one of negatively correlated parameters. For both ULS and SLS, the assumption of nonnormal distribution for the random variables has almost no effect on the reliability index for the practical range of values of the applied pressure. Finally, it was found that the system reliability depends on both limit states. Notice however that the contribution of ULS to the system reliability was not significant. Thus, SLS can be used alone for the assessment of the tunnel reliability. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000060 [article] Probabilistic analysis of circular tunnels in homogeneous soil using response surface methodology [texte imprimé] / Guilhem Mollon, Auteur ; Daniel Dias, Auteur ; Abdul-Hamid Soubra, Auteur . - 2009 . - pp. 1314–1325. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 9 (Septembre 2009) . - pp. 1314–1325 Mots-clés : ShieldsTunnelingSettlementServiceabilityUltimate  loadsLimit  statesSystem  reliability Résumé : A probabilistic analysis of a shallow circular tunnel driven by a pressurized shield in a frictional and/or cohesive soil is presented. Both the ultimate limit state (ULS) and serviceability limit state (SLS) are considered in the analysis. Two deterministic models based on numerical simulations are used. The first one computes the tunnel collapse pressure and the second one calculates the maximal settlement due to the applied face pressure. The response surface methodology is utilized for the assessment of the Hasofer-Lind reliability index for both limit states. Only the soil shear strength parameters are considered as random variables while studying the ULS. However, for the SLS, both the shear strength parameters and Young’s modulus of the soil are considered as random variables. For ULS, the assumption of uncorrelated variables was found conservative in comparison to the one of negatively correlated parameters. For both ULS and SLS, the assumption of nonnormal distribution for the random variables has almost no effect on the reliability index for the practical range of values of the applied pressure. Finally, it was found that the system reliability depends on both limit states. Notice however that the contribution of ULS to the system reliability was not significant. Thus, SLS can be used alone for the assessment of the tunnel reliability. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000060

Validation of a new 2D failure mechanism for the stability analysis of a pressurized tunnel face in a spatially varying sand / Guilhem Mollon in Journal of engineering mechanics, Vol. 137 N° 1 (Janvier 2011) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 137 N° 1 (Janvier 2011) . - pp.8-21 Titre : Validation of a new 2D failure mechanism for the stability analysis of a pressurized tunnel face in a spatially varying sand Type de document : texte imprimé Auteurs : Guilhem Mollon, Auteur ; Phoon, Kok-Kwang, Auteur ; Daniel Dias, Auteur Année de publication : 2011 Article en page(s) : pp.8-21 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Tunnels  Limit  analysis  Failures  Shear  strength  Parameters. Résumé : A new two-dimensional (2D) limit analysis failure mechanism is presented for the determination of the critical collapse pressure of a pressurized tunnel face in the case of a soil exhibiting spatial variability in its shear strength parameters. The proposed failure mechanism is a rotational rigid block mechanism. It is constructed in such a manner to respect the normality condition of the limit analysis theory at every point of the velocity discontinuity surfaces taking into account the spatial variation of the soil angle of internal friction. Thus, the slip surfaces of the failure mechanism are not described by standard curves such as log-spirals. Indeed, they are determined point by point using a spatial discretization technique. Though the proposed mechanism is able to deal with frictional and cohesive soils, the present paper only focuses on sands. The mathematical formulation used for the generation of the failure mechanism is first detailed. The proposed kinematical approach is then presented and validated by comparison with numerical simulations. The present failure mechanism was shown to give results (in terms of critical collapse pressure and shape of the collapse mechanism) that compare reasonably well with the numerical simulations at a significantly cheaper computational cost. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.org/emo/resource/1/jenmdt/v137/i1/p8_s1?isAuthorized=no [article] Validation of a new 2D failure mechanism for the stability analysis of a pressurized tunnel face in a spatially varying sand [texte imprimé] / Guilhem Mollon, Auteur ; Phoon, Kok-Kwang, Auteur ; Daniel Dias, Auteur . - 2011 . - pp.8-21. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 137 N° 1 (Janvier 2011) . - pp.8-21 Mots-clés : Tunnels  Limit  analysis  Failures  Shear  strength  Parameters. Résumé : A new two-dimensional (2D) limit analysis failure mechanism is presented for the determination of the critical collapse pressure of a pressurized tunnel face in the case of a soil exhibiting spatial variability in its shear strength parameters. The proposed failure mechanism is a rotational rigid block mechanism. It is constructed in such a manner to respect the normality condition of the limit analysis theory at every point of the velocity discontinuity surfaces taking into account the spatial variation of the soil angle of internal friction. Thus, the slip surfaces of the failure mechanism are not described by standard curves such as log-spirals. Indeed, they are determined point by point using a spatial discretization technique. Though the proposed mechanism is able to deal with frictional and cohesive soils, the present paper only focuses on sands. The mathematical formulation used for the generation of the failure mechanism is first detailed. The proposed kinematical approach is then presented and validated by comparison with numerical simulations. The present failure mechanism was shown to give results (in terms of critical collapse pressure and shape of the collapse mechanism) that compare reasonably well with the numerical simulations at a significantly cheaper computational cost. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.org/emo/resource/1/jenmdt/v137/i1/p8_s1?isAuthorized=no