Influence of the strength of rock-like models on the local deformation field and acoustic emission characteristics

The deformation characteristics of fractured rock masses and the acoustic emission (microseismic) characteristics of crack propagation can help evaluate and predict the stability of rock masses. Rock-like materials with different strengths were designed using quartz sand, barite powder, and gypsum; models with a single flaw and the same properties were prefabricated to perform uniaxial compression tests. Based on the stress–strain relationship of the models, the deformation process could be divided into four stages: medium compaction stage (I), elastic deformation stage (II), crack propagation stage (III), and model failure stage (IV). The temporal variation trends in the maximum principal strain on both sides of the pre-existing fracture were the same. The range of the local strain deflection angle at the passive loading end increased, and the peak relative displacement rate decreased with the increase of strength of the model. Ring-down count vs time curve could be divided into three stages: initial, growth, and stable stages. The initial stage corresponded to deformation Stage I and II. The high-strength model showed calm ring-down count in this stage. The growth stage corresponded to Stage III, where the higher the model strength, the higher the growth rate of the cumulative ring-down counts. The stable stage corresponded to Stage IV, where the cumulative ring-down counts were either stable or increased steadily. Overall, the peak frequency distribution tended to widen with the decrease in the model strength. The results can serve as an experimental basis to understand the deformation and damage mechanisms of rock masses.