Continuum modelling of dynamic behaviour and fragmentation of quasi-brittle materials: application to rock fragmentation by blasting

Fragmentation plays an important role in a wide variety of industrial processes such as blasting, demolition, crushing, cutting, etc., in which one desires to cause fragmentation in the most efficient and controlled manner. Nevertheless, a consistent theoretical description of this process is not yet available. In this paper, we present a computational methodology to simulate both the behaviour and the fragmentation of quasi-brittle materials, such as rocks and concrete, under dynamic loadings. We consider that the fragmentation process is a natural extension of the fracture process. In order to describe the dynamic fracture process, a suitable phenomenological constitutive model is developed and implemented in a finite element code. Concerning the dynamic fragmentation, a general formulation of predicting the fragment size distribution is provided. This formulation is based on a post-processing analysis of the history of the material's thermodynamic state. The complete approach is then applied to the modelling of the fragmentation of chamber blasting tests of limestone cylindrical samples.