Developments to the Bonded Block Modeling technique for Discrete Element simulation of transversely isotropic rocks

Abstract

In this research, a novel three-dimensional Bonded Block Model (BBM) for the Discrete Element Method is proposed for the simulation of transversely isotropic rocks. The model stands on three new developments proposed to the conventional BBM: the adoption of Rigid Body Spring Network (RBSN) bonds combined with a fictitious stress method for the realization of transversely isotropic elastic behavior; a replaceable particle scheme for the explicit representation of cleavage fracture; and a dual Cohesive Zone Model for the simulation of fracture propagation on cleavage and rock matrix according to non-linear fracture mechanics theory. The model is verified by comparing numerical unconfined compression, direct tension and three point bending tests’ results with analytical and finite element solutions, and it is validated against laboratory data reported in literature for three transversely isotropic rock types. The results show that the improved BBM provides for mesh objective numerical representation of the anisotropy in deformability, peak strength and mode-I non-linear fracture mechanics properties of transversely isotropic rocks. In addition, the new model manifests realistic failure modes and the macroscale properties can be defined directly, without trial-and-error calibrations.