The Effect of Consolidation on TBM Shield Loading in Water-Bearing Squeezing Ground

Ramoni, M.; Anagnostou, G.

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The Effect of Consolidation on TBM Shield Loading in Water-Bearing Squeezing Ground

Ramoni, M. ; Anagnostou, G.

In: Rock Mechanics and Rock Engineering, 2011, vol. 44, no. 1, p. 63-83

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Titre

The Effect of Consolidation on TBM Shield Loading in Water-Bearing Squeezing Ground

Auteur

Ramoni, M.. ETH Zurich, Zurich, Switzerland
Anagnostou, G.. ETH Zurich, Zurich, Switzerland

Type de document

Postprint

Langue

Inglese

Publié dans

Rock Mechanics and Rock Engineering, 2011, vol. 44, no. 1, p. 63-83. Springer Vienna

Autre version électronique

Publisher's version : https://doi.org/10.1007/s00603-010-0107-4

Classification

Technologie, Sciences de l'ingénieur

Mots clés

Tunnel boring machine ; Squeezing ground ; Shield jamming ; Advance rate ; Standstill ; Consolidation ; Numerical investigation ; Steady state method ; A : Field function (co-ordinate system fixed to the advancing tunnel face) ; A * : Field function (co-ordinate system spatially fixed) ; b j : Body force vector ; c g : Compressibility of the rock or soil grains ; c w : Compressibility of the water ; D : Boring diameter ; e : Extrusion rate of the core ; E : Young's modulus of the ground ; { f } : Nodal force vector ; F b : Boring thrust force ; F c : Maximum cutter force ; f c : Uniaxial compressive strength of the ground ; F f : Thrust force needed for overcoming friction ; F i : Installed thrust force ; F r : Required thrust force ; H : Hydraulic head ; { h } : Nodal hydraulic head vector ; [ H ] : Permeability matrix ; h 0 : Initial hydraulic head ; h 0 * : Reduced initial hydraulic head ; k : Ground permeability ; [ K ] : Stiffness matrix ; K l : Lining stiffness ; K s : Shield stiffness ; L : Shield length ; [ L ] : Coupling matrix ; N : Surface normal ; n c : Number of cutters ; n g : Ground porosity ; p : Ground pressure ; P : Penetration ; p w : Pore water pressure ; p w,0 : Initial pore water pressure ; { q } : Nodal source vector ; Q : Water flow ; q k : Flux vector (co-ordinate system fixed to the advancing tunnel face) ; q k * : Flux vector (co-ordinate system spatially fixed) ; q n : Boundary flux ; r : Cutter head rotational speed ; R : Tunnel radius ; R m : Outer radius of the axially symmetric computational domain ; t : Time ; t crit : Critical duration of a standstill ; u : Radial displacement of the ground at the tunnel boundary ; { u } : Nodal displacement vector ; u e : Extrusion of the core ; [ V ] : Additional matrix used by the steady state method ; v : Advance rate ; v n : Net advance rate ; [ W ] : Additional matrix used by the steady state method ; x : Radial co-ordinate (distance from the tunnel axis) ; x k : Position vector (co-ordinate system fixed to the advancing tunnel face) ; x k * : Position vector (co-ordinate system spatially fixed) ; y : Axial co-ordinate fixed to the advancing tunnel face (distance behind the tunnel face) ; y * : Axial co-ordinate spatially fixed ; z : Elevation ; Δ R : Size of the radial gap between shield and bored profile ; Δ R l : Size of the radial gap between lining and bored profile ; α : Utilization degree of the TBM ; ε kk : Volumetric strain (co-ordinate system fixed to the advancing tunnel face) ; ε kk * : Volumetric strain (co-ordinate system spatially fixed) ; γ w : Unit weight of the water ; φ : Angle of internal friction of the ground ; μ : shield skin friction coefficient ; ν : Poisson's ratio of the ground ; σ : Stress ; σ 0 : Initial stress ; σ ij : Stress tensor (co-ordinate system fixed to the advancing tunnel face) ; σ ij * : Stress tensor (co-ordinate system spatially fixed) ; ψ : Dilatancy angle of the ground

Identifiant OAI-PMH

oai:doc.rero.ch:313764

Summary

Jamming or overstressing of the shield due to ground pressure are potential problems for tunnel boring machine (TBM) tunnelling in squeezing ground. The risk of shield jamming depends essentially on the deformation rate of the ground in the vicinity of the working face. The time-dependency of the ground response to the excavation is associated with its rheological properties as well as with the transient consolidation process that takes place around the opening in the case of a low-permeability saturated ground. The present paper focuses on the second mechanism and investigates the interaction between the advancing shield, tunnel lining and consolidating ground by means of transient numerical analyses. For a given set of geotechnical conditions and a given TBM configuration, the load exerted by the ground upon the shield during TBM operation decreases with increasing gross advance rate. During a long break in operations, the ground pressure may increase significantly, thereby necessitating a higher thrust force to overcome shield skin friction and restart the TBM. It is interesting to note that a high advance rate reduces the risk of shield jamming not only during TBM advance, but is also favourable with respect to any subsequent long standstills

The Effect of Consolidation on TBM Shield Loading in Water-Bearing Squeezing Ground

Ramoni, M. ; Anagnostou, G.

In: Rock Mechanics and Rock Engineering, 2011, vol. 44, no. 1, p. 63-83

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The Effect of Consolidation on TBM Shield Loading in Water-Bearing Squeezing Ground

Ramoni, M. ; Anagnostou, G.

In: Rock Mechanics and Rock Engineering, 2011, vol. 44, no. 1, p. 63-83

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