Abstract
At the laboratory scale, locating acoustic emission (AE) events is a comparatively mature method for evaluating cracks in rock materials, and the method plays an important role in numerical simulations. This study is aimed at developing a quantitative method for the measurement of acoustic emission (AE) events in numerical simulations. Furthermore, this method was applied to estimate the crack initiation, propagation, and coalescence in rock materials. The discrete element method-acoustic emission model (DEM-AE model) was developed using an independent subprogram. This model was designed to calculate the scalar seismic tensor of particles in the process of movement and further to determine the magnitude of AE events. An algorithm for identifying the same spatiotemporal AE event is being presented. To validate the model, a systematic physical experiment and numerical simulation for argillaceous sandstones were performed to present a quantitative comparison of the results with confining pressure. The results showed good agreement in terms of magnitude and spatiotemporal evolution between the simulation and the physical experiment. Finally, the magnitude of AE events was analyzed, and the relationship between AE events and microcracks was discussed. This model can provide the research basis for preventing seismic hazards caused by underground coal mining.
Highlights
An increasing number of underground engineering and physical experiments have focused on investigating the failure or fracture properties of rocks [1, 2]
The results showed good agreement in terms of magnitude and spatiotemporal evolution between the simulation and the physical experiment
Under the different confining pressures, the results showed good agreement for the ratio of cumulative acoustic emission (AE) events in the physical experiments and in the DEM-AE model
Summary
An increasing number of underground engineering and physical experiments have focused on investigating the failure or fracture properties of rocks [1, 2]. An understanding of the characteristics of AE in the process of crack propagation in rock materials helps to prevent underground engineering hazards, such as rock burst [3, 4], mining tremor [5], roadway rib spalling [6], and similar events. Among the numerical methods that have been used to study the deformation and cracks in rock materials, the finite element method (FEM) or Fast Lagrangian Analysis of Continua (FLAC) cannot generate actual cracks, and the majority of investigations have focused mainly on studying the plastic or damaged zones [12, 13]. The detection of AE events during the deformation process in rock materials is a powerful tool for the quantitative analysis of cracks, the AE characteristics cannot be derived directly from numerical simulations [16], and a new module using an independent subprogram is needed. Based on the FEM/DEM method, Lisjak et al [17] proposed a new model to simulate
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