Journal
GEOTECHNIQUE
Volume 72, Issue 12, Pages 1113-1128Publisher
ICE PUBLISHING
DOI: 10.1680/jgeot.20.P.247
Keywords
anisotropy; COx clay-stone; finite-element methods; fractured zone; non-local; numerical modelling; sensitivity analysis; strain localisation; tunnels
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Funding
- Conacyt scholarship [270190]
- French national radioactive waste management agency (Andra)
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This study presents a sensitivity analysis on the simulation of an underground excavation in the COx argillaceous formation. The analysis considers various parameters such as initial stress, strength and stiffness anisotropy, and hydraulic and hydromechanical parameters. The results provide a better understanding of the hydromechanical mechanisms associated with underground excavations in COx claystone and similar materials.
A sensitivity study is presented to evaluate the influence of different parameters on the simulation of an underground excavation in the Callovo-Oxfordian (COx) argillaceous formation performed in the Meuse/Haute-Marne underground research laboratory. An elasto-viscoplastic constitutive law representing the characteristic behaviour of indurated mudrocks and stiff clays has been employed. It incorporates anisotropy, strain-softening, creep deformations and dependence of permeability on damage. In addition, a non-local formulation, able to simulate localised deformations objectively, has been incorporated in the analyses. The following features affecting the excavation have been studied: initial stress, strength and stiffness anisotropy, strength parameters, hydraulic and hydromechanical parameters, and scale effects. A simulation reported in a companion paper provides the base case for benchmarking. The results are compared in terms of extent and configuration of the excavation fractured zone, vertical and horizontal tunnel convergences, and the development and evolution of pore pressures in the rock. From the comparisons, an enhanced understanding of the hydromechanical mechanisms associated with underground excavations in COx claystone, and other similar argillaceous materials, has been achieved.
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