Numerical modelling of a Brazilian Disc test of layered rocks using the combined finite-discrete element method

Rock Engineering 2009 - Rock Engineering in Difficult Conditions
Giovanni Grasselli, Ante Munjiza,
Abstract The scope of this study is to simulate the behaviour of a layered rock sample under standard laboratory Brazilian Disc test using an innovative combined finite-discrete element method (FEM/DEM) research code, “Y2D” (Munjiza, 2004). In Y2D code, each discrete element is discretized into finite elements. With this numerical approach it is possible to explicitly reproduce the continuum-discontinuum behaviour of geomaterials; the continuum behaviour is modelled through finite elements while discontinuous behaviour is analysed by discrete elements. Contact (detection and interaction) between individual bodies, deformability and fracture of these bodies are the key processes in FEM/DEM. In this context, transition from continua to discontinua is done through fracture and fragmentation processes. In Y2D code, these processes are modelled using the combined single and smeared crack model also known as the discrete crack model.

In this contribution we present numerical results that reproduce the main behaviour observed in the laboratory during Brazilian indirect tensile tests. The influence of layering and the direction of loading on the samples behaviour are studied through various layering and loading configurations. A parametric study including the effect of loading rate on the results and sensitivity to mesh size has been carried out. We have demonstrated the suitability of the numerical approach to explicitly model rock deformation and failure.



References
Munjiza, A. (2004). The combined finite-discrete element method. Hoboken, NJ: Wiley.
Keywords: combined finite-discrete element method (FEM/DEM), Brazilian Disc Test, Tensile strength, Numerical modelling, Layered rocks
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