Abstract: Based on the particle flow code platform, using image processing technology and Monte Carlo method, a discrete fracture network is generated. Combined with the grain-based model, the numerical modeling of the granite mesostructure is carried out. Then from a micro perspective, the effect of the discrete fracture network on rock strength and deformation properties and acoustic emission characteristics is described. The main conclusions are as follows: (1) The average length and density of the fractures affect the mechanical properties of the rock. The uniaxial compressive strength and elastic modulus of the rock decrease with the increase of the fracture density. (2) Rock failure under uniaxial compression is dominated by intergranular tensile cracks and intragranular tensile cracks. (3) The discrete fracture network is closely related to the acoustic emission events of the rock. With the increase of fracture density, the b value of acoustic emission and the D value of fractal dimension both show a downward trend. The sharp drop of b and D indicate that the rock instability failure. (4) The discrete fracture network has a certain influence on the magnitude of acoustic emission events. Acoustic emission events with high rupture intensity are prone to occur near discrete fracture networks. In summary, conclusions based on the mesoscopic rock fracture mechanism and acoustic emission phenomena obtained from the joint modeling of discrete fracture networks and grain-based models can effectively make up for the shortcomings of existing research methods in laboratory experiments and provide strong support for the stability evaluation and engineering construction of rock mass with more complex fracture network in the field.

Key words: discrete fracture network, grain-based model, acoustic emission, granite, particle flow code simulation