An energy-based model with non-symmetrical branch fractures of different roughness

The fracture surface regarded as the three-dimensional morphological characteristics of crack propagation is formed under the impetus of energy, and its characteristics can be described by the fracture surface roughness. Investigating the fracture surface roughness is of high importance for prediction and assessment of earthquakes, calculating shear strength at the fracture zone, and comprehending fluid flow. However, an excess of available energy flowing to the crack tip would cause crack branching, and the influence of the energy on fracture surface roughness of branching is rarely considered. This paper aims to evaluate the effect of the dissipated energy on fracture surface roughness based on rock dynamic fracture experimental study of crack branching. A set of split Hopkinson pressure bar measuring systems (SHPB-PS50) for rock dynamic fracture tests was established. The morphological characteristics of crack branching on the specimen surface, the three-dimensional surface topography of the fracture surface, and the changes in the dissipated energy characteristics with the fracture surface roughness were analyzed. It is concluded that the attenuation function is suitable for expressing the relationship between the roughness parameters and the dissipated energy, and an energy model with non-symmetrical branching of different roughness is established. Additionally, a numerical simulation analytical approach is developed for building the fracture surfaces through the coordinates of the discrete fracture network to measure roughness. The numerical simulation results support the experimental conclusions. The energy-based model with non-symmetrical branch fractures of different roughness is correct.