Fracture Characteristics of Orebody Rock with Varied Grade Under Dynamic Brazilian Tests

Abstract

In mining engineering, the grade of the orebody significantly influences mining activities. Typically, the grade of completed mine sequences can be used to estimate the yearly mine’s production and profit. However, the strength of orebody varies in different parts of the mine, as demonstrated by the requirement for different blast design. The degree of rock fragmentation cannot be accurately predicted after production blasts; in addition, secondary breakage of oversized rock affects the mining plan. In this study, split Hopkinson pressure bar tests were conducted to obtain the dynamic tensile strength and fracture energy of orebody rock having different grades. The fracture surfaces were obtained using a 3D scanner and surface roughness was estimated on the basis of fractal dimensions. The failure process of ore rock was reproduced through the flat-joint model (FJM) in PFC2D on the basis of microscopic and macroscopic images of the fracture surface using a special FJM structure. Physical experiments and numerical simulations indicated that the mechanical properties and fracture characteristics of the orebody rock vary with its grade. This difference should be considered during mining activities, specifically in blast and draw point designs.