Comparative numerical calculations in the context of tunnel design for nuclear waste repositories in Opalinus Clay
Comparative numerical calculations in the context of tunnel design for nuclear waste repositories in Opalinus Clay
The hydro-mechanical (HM) response of the host rock selected for the Swiss geological repository for radioactive waste, the Opalinus Clay (OPA), is complex, and its description requires advanced constitutive models. However, for the tunnel design, a simple design-orientated approach is envisaged. The present study uses the eADP constitutive model for numerical tunnel analyses. It considers most aspects of the OPA mechanical behaviour, such as anisotropic stiffness and strength, post-peak softening, and pre-peak anisotropic hardening. The model has been calibrated on an experimental dataset composed of 13 triaxial tests. The study focuses on the effect of softening on tunnel design aspects under project-specific conditions. It includes comparative HM FEM plane strain computations of tunnel excavations with and without post-peak softening. Displacements of the tunnel boundary and internal actions of the lining were computed for long-term conditions. The paper shows that, for high initial stresses and rock strength typical for OPA, the results obtained with a perfect plastic approach considering the residual strength are close to those obtained considering softening behaviour.
A. Madaschi; Julia Leuthold; Linard Cantieni; Lyesse Laloui
10th European Conference on Numerical Methods in Geotechnical Engineering (NUMGE2023)
10. Tunnelling and mining applications
https://doi.org/10.53243/NUMGE2023-127
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