A Two-Dimensional Planar Fracture Network Model for Broken Rock Mass Based on Packer Test and Fractal Dimension

Abstract

Broken rock masses with the complexity and concealment widely exist in nature such as underground mine, collapse column, and zone. It is extremely difficult to model fracture networks and to simulate water diffusion for broken rock masses. To explore a reasonable fracture network model for broken rock masses, a new method for modeling a two-dimensional planar fracture network model is proposed in this paper. It includes packer test, empirical relationship, fractal width description, and symmetric expansion modeling. Then, the fluid-solid coupling is used to simulate the diffusion properties of water in the two-dimensional planar fracture network model. It is found that the diffusion velocities $v_{\max }$ and $v_{\min }$ do not appear in the fracture widths ${\lambda }_{\max }$ and ${\lambda }_{\min }$. It indicates that the fracture widths ${\lambda }_{\max }$ and ${\lambda }_{\min }$ in the fracture network model for broken rock mass have little impact on the diffusion velocity. Furthermore, the fracture distribution pattern in the fracture network model is an important factor affecting the diffusion velocities $v_{\max }$ and $v_{\min }$. The simulation results of water diffusion in the currently proposed model are almost consistent with the actual process of the packer test. Also, the validity of the two-dimensional planar fracture network model is verified by comparing the simulation results with the existing research.