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Effect of soil conditioners on the pressure and rate-dependent shear strength of different clays / R. Zumsteg in Journal of geotechnical and geoenvironmental engineering, Vol. 138 N° 9 (Septembre 2012) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 9 (Septembre 2012) . - pp.1138–1146. Titre : Effect of soil conditioners on the pressure and rate-dependent shear strength of different clays Type de document : texte imprimé Auteurs : R. Zumsteg, Auteur ; M. Plotze, Auteur ; A. M. Puzrin, Auteur Année de publication : 2012 Article en page(s) : pp.1138–1146. Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Soil  conditioning  Clay  pastes  Vane  shear  test  Viscosity  of  clays  Clay-polymer  mixtures  Earth  pressure  balance Résumé : Tunneling using the earth pressure balance machines method in clayey soils requires the addition of conditioning chemicals to reduce the torque moment of the machine and to guarantee a safe and economical excavation process. Injection of foams and polymers at the cutter head of the tunnel boring machine with subsequent remolding in the pressure chamber transforms the excavated material into a deformable soil paste with preferably low strength and adhesion. The soil becomes more compressible and can develop viscous properties, such that the pressure and rate dependency of the shear strength of the mixtures are of major importance for the proper design and analysis of the tunneling processes. In this paper, the results of vane shear strength measurements on various conditioned clays and clay-sand mixtures at various shearing velocities and applied pressures are presented and analyzed. The results clearly show the effects of the chemicals used and also point out the differences in their efficiency depending on the clay mineralogy. This allows for an improved understanding of the working mechanisms of the chemicals. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000681 [article] Effect of soil conditioners on the pressure and rate-dependent shear strength of different clays [texte imprimé] / R. Zumsteg, Auteur ; M. Plotze, Auteur ; A. M. Puzrin, Auteur . - 2012 . - pp.1138–1146. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 9 (Septembre 2012) . - pp.1138–1146. Mots-clés : Soil  conditioning  Clay  pastes  Vane  shear  test  Viscosity  of  clays  Clay-polymer  mixtures  Earth  pressure  balance Résumé : Tunneling using the earth pressure balance machines method in clayey soils requires the addition of conditioning chemicals to reduce the torque moment of the machine and to guarantee a safe and economical excavation process. Injection of foams and polymers at the cutter head of the tunnel boring machine with subsequent remolding in the pressure chamber transforms the excavated material into a deformable soil paste with preferably low strength and adhesion. The soil becomes more compressible and can develop viscous properties, such that the pressure and rate dependency of the shear strength of the mixtures are of major importance for the proper design and analysis of the tunneling processes. In this paper, the results of vane shear strength measurements on various conditioned clays and clay-sand mixtures at various shearing velocities and applied pressures are presented and analyzed. The results clearly show the effects of the chemicals used and also point out the differences in their efficiency depending on the clay mineralogy. This allows for an improved understanding of the working mechanisms of the chemicals. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000681