Influence of defect hole location on acoustic emission characteristics and damage evolution of rocks: a numerical study based on particle flow code

In this paper, the mechanical properties, acoustic emission characteristics and damage evolution laws of rocks with different defect holes are explored by considering the influence of the location of defect holes. The rock models with different defect hole locations are constructed based on particle flow code. The influence of different defect hole positions on the mechanical characteristics, acoustic emission (AE) characteristics, damage evolution process, and failure modes of rock models are discussed. The research result shows that the elastic modulus (E) of numerical models with different defect hole locations has little change; the uniaxial compressive strength (UCS) of the model with defect hole at the center of the model is larger than the UCS of the defect hole at the boundary of the model; the evolution law of acoustic emission can be roughly divided into three stages: the silent emission stage, the slow development stage and the rapid development stage. The position of defect holes has little influence on the first two stages, but has obvious influence on the third stage, such as the intensity of acoustic emission (maximum AE counts) and strain range. The position of different defect holes has little influence on the first two stages of damage evolution of rock models, but mainly affects the rapid damage stage. The position of the defect hole has little effect on the crack initiation position of the rock, both in the upper and lower directions of the circular hole. However, the location of the defect hole will affect the failure process of the rock.