Block caving-induced strata movement and associated surface subsidence: a numerical study based on a demonstration model

The block cave mining mechanism and associated subsidence present one of the most challenging engineering problems in rock mining. Although block caving has been in use for many years, there has been limited research on the impact caving angles have on surface settlement and failure profiles, specifically when associated with deep caves and surface propagation (i.e., not as part of caving into an existing open pit). We analyse in this study block caving-induced step-path failure development in a large-scale demonstration model utilizing a numerical code based on a finite element technique that incorporates an elasto-brittle fracture mechanics constitutive criterion. Fracture initiation, propagation and coalescence, as well as the breaking of the intact rock bridge and the evolution of a pressure-balancing arch in the stressed strata, are represented visually during the whole caving process. Based on numerical results, surface impacts of block caving, such as subsidence profiles, break angles, fracture initiation angles and subsidence angles at different initial caving depths, are illustrated in this study.