Abstract
Rock has the characteristics of natural heterogeneity and discontinuity. Its failure phenomenon induced by external force involves complex processes, including the microcrack initiation, propagation, coalescence, and the macrocrack formation. In this study, the Weibull random distribution based on the rock microstructure characteristics is introduced into the combined finite-discrete element method (FDEM) to establish the heterogeneous rock model, and the mechanical response and damage evolution of rock samples in uniaxial compression test are simulated. The results show that FDEM simulation with loaded heterogeneous rock model can reflect the progressive development of rock damage, fracture, and acoustic emission (AE) activity in real rock well. Meanwhile, the statistical analysis indicates that the number and energy evolution of AE events with different fracture modes in the model are consistent with the macroscopic failure mode of rock. The change of b-value also agrees with the increasing trend of high-energy events in the loading process. This method provides a new tool for the analysis of rock damage and fracture evolution.
Highlights
Rock is a kind of natural heterogeneous and discontinuous medium
E combined finite-discrete element method (FDEM) proposed by Munjiza et al [1, 2] combines the advantages of finite element and discrete element, in which the continuous mechanical behaviors, such as elastic-plastic deformation of materials, can be simulated by the finite element method, while the discontinuous deformation behaviors such as damage and fracture can be analyzed by the softening failure of crack element and the contact calculation of blocks used in the discrete element method. e method can simulate the failure process of rock from continuity to discontinuity
In order to establish a heterogeneous rock model and simulate acoustic emission (AE) activity in the process of rock macrofailure development, this study introduces the Weibull distribution which is widely used in cumulative damage statistics [19] into the open-source code, FDEM
Summary
Rock is a kind of natural heterogeneous and discontinuous medium. Under the influence of external force, microcracks in rock gradually initiate, propagate, nucleate, coalesce, and form the macrocracks. e complex process corresponds to a trans-scale mechanical behavior from the microcosmic to the macroscopic, which involves the rock deformation, fracture, interaction of rock blocks, and further fragmentation in interaction process. E combined finite-discrete element method (FDEM) proposed by Munjiza et al [1, 2] combines the advantages of finite element and discrete element, in which the continuous mechanical behaviors, such as elastic-plastic deformation of materials, can be simulated by the finite element method, while the discontinuous deformation behaviors such as damage and fracture can be analyzed by the softening failure of crack element and the contact calculation of blocks used in the discrete element method. E method can simulate the failure process of rock from continuity to discontinuity. A new modelling method of rock heterogeneity in FDEM is proposed referring to Lisjak et al [3], and rock damage evolution and acoustic emission (AE) phenomenon in uniaxial compression test are simulated
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