Study into the TBM jamming hazard in Opalinus clay

The National Cooperative for the Disposal of Radioactive Waste (Nagra) in Switzerland has designated Opalinus clay as a host rock for a deep geological repository. The drifts for high-level waste storage (∅ 3.5 m) are to be constructed with a shielded tunnel boring machine (TBM) at depths where sque...

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Veröffentlicht in:Expanding Underground - Knowledge and Passion to Make a Positive Impact on the World S. 2146 - 2153
Hauptverfasser: Nordas, A.N., Natale, M., Anagnostou, G., Cantieni, L.
Format: Buchkapitel
Sprache:Englisch
Veröffentlicht: United Kingdom CRC Press 2023
Taylor & Francis Group
Ausgabe:1
Schlagworte:
Vice Versa
Advancing Tunnel Face
Overburden
Pore Pressure
Excess Pore Pressure Dissipation
TBM Advance
GRCs
Tunnel Face
Vertical Symmetry Plane
Opalinus Clay
Tunnel Boundary
TBM Shield
Material Anisotropy
Deep Geological Repositories
Shield Jamming
BIM Model
Stiffness Anisotropy
Early Middle Jurassic Period
Pore Pressure Field
Ground Consolidation
Shield Tail
SEM
Negative Pore Pressures
Excess Pore Pressures
Squeezing Conditions
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Zusammenfassung:The National Cooperative for the Disposal of Radioactive Waste (Nagra) in Switzerland has designated Opalinus clay as a host rock for a deep geological repository. The drifts for high-level waste storage (∅ 3.5 m) are to be constructed with a shielded tunnel boring machine (TBM) at depths where squeezing conditions may occur and the ground is fully saturated. This paper studies the TBM shield jamming hazard during excavation or long TBM standstills by means of 3D, transient, coupled hydraulic-mechanical Finite Element computations. An anisotropic linearly elastic and perfectly plastic constitutive model with a Mohr Coulomb yield condition is adopted for the Opalinus clay. Of practical interest is the influence of anisotropy and ground desaturation on the time-dependent ground deformations after excavation. The study concludes that shield jamming is not critical. The results offer practical guidance for the identification of critical design aspects for underground systems in pronouncedly anisotropic ground.
DOI:10.1201/9781003348030-258