Three-dimensional FDEM numerical simulation of failure processes observed in Opalinus Clay laboratory samples

• Main Authors: Omid Mahabadi, Patrick Kaifosh, Paul Marschall, Tim Vietor
• Format: Article
• Language: English
• Published: Elsevier 2014-12-01
• Series: Journal of Rock Mechanics and Geotechnical Engineering
• Subjects: Three-dimensional (3D) hybrid finite-discrete element method (FDEM); Intermediate principal stress; Discrete element methods; True triaxial behaviour; Failure envelope
• Online Access: http://www.sciencedirect.com/science/article/pii/S1674775514000882

This study presents the first step of a research project that aims at using a three-dimensional (3D) hybrid finite-discrete element method (FDEM) to investigate the development of an excavation damaged zone (EDZ) around tunnels in a clay shale formation known as Opalinus Clay. The 3D FDEM was first calibrated against standard laboratory experiments, including Brazilian disc test and uniaxial compression test. The effect of increasing confining pressure on the mechanical response and fracture propagation of the rock was quantified under triaxial compression tests. Polyaxial (or true triaxial) simulations highlighted the effect of the intermediate principal stress (σ2) on fracture directions in the model: as the intermediate principal stress increased, fractures tended to align in the direction parallel to the plane defined by the major and intermediate principal stresses. The peak strength was also shown to vary with changing σ2.