Discrete Element Modelling of Shale as a Transversely Isotropic Rock

DEM is now recognized as a powerful tool for simulating behaviors in rock mechanics. In particular, bonded particle model has been successfully applied in emulating the elastic modulus, Poisson's ratio and strength parameters of isotropic rock by controlling the microparameters in DEM model. In this study, the smooth joint contact model was introduced to represent the bedding planes in order to eventually model the transversely isotropic rock. Consideration of anisotropy is important for shale gas production because shale is shown to have a significant anisotropy in terms of elastic constants and compressive and tensile strengths. The chosen anisotropy model is transversely isotropic model which is believed to model the mechanical behavior of shale to a reasonable extent. The properties of Boryeong shale (Cho. et al., 2012) were used as a reference for transversely isotropic rock. Transversely isotropic rock model using DEM behaved in good agreement with the mechanical behaviors of Boryeong shale from the laboratory. The results can be evidence that development of anisotropic numerical model is promising through DEM. This anisotropic modelling is expected to pave the way for wide variety of engineering application ranging from traditional rock mechanics application to the emerging applications such as shale gas production.