Rock failure progressive processes in static tests and dynamic impact tests are modelled using a hybrid finite-discrete element method. The simulated results are then compared with these recorded in literatures to calibrate the hybrid method. After that, the hybrid finite-discrete element method is applied to model rock excavation in mechanical cutting. Throughout this study, it is concluded that the hybrid finite-discrete element method is superior to the continuum-based finite element method and the discontinuum-based discrete element method in terms of modelling rock failure progressive process and resultant fragment flow, and may be a valuable numerical tool for optimizing the design of rock cutting and drilling equipments.
Rock failure has important applications in mechanical excavation, rock blasting, hydraulic fracturing and geostructure instability. Correspondingly, rock failure progressive analysis has been one of the hottest research topics in the field of rock mechanics and rock engineering during past decades. With rapid development of computational geomechanics, numerical method has become a powerful tool for analysing rock failure progressive process.
According to a review on numerical models in geomechanics, the numerical method for rock failure can be classified as continuum, discontinuum and coupled continuum-discontinuum methods. Continuum method such as finite element method (FEM) has been the most widely used numerical method in geomechanics. However, the modelling of rock fracture is associated with localisation of strains, loss of ellipticity of the governing equation, ill-posed problems and general sensitivity to mesh size and mesh orientation, which the standard continuum mechanics formulations fails to deal with. As a results, various enriched continuum methods are developed on the basis of damage mechanics, micro-polar Cosserat or higher-order constitutive law to deal with the rock failure. However, in spite of various enrichments, the continuum method has still difficulty in modelling the rock failure, especially dealing with fragment muck-piling after failure.