Simulating flow in rock joints using a particulate interface model of a discrete element method

This study proposes a fluid flow algorithm incorporated with the particulate interface model (PIM) to simulate flow in rock joints in the particulate DEM. The PIM captures the mechanical behavior of a rock joint based on macroscopic parameters, and then the fluid flow algorithm calculates correct flow behavior in rock joint. In the fluid flow algorithm, a virtual pore space is defined as the area that is surrounded by adjacent particles in contacts. A series of pore spaces are connected to form a flow channel along a joint, and fluid is only transmitted in the designated joint. A series of numerical flow tests through a joint under different normal and shear stresses are conducted. A comparison of analytical solutions under different times and hydraulic conductivities reveals that the proposed model can simulate flow in a single joint in both steady and transient states. In addition, two cases that involve multiple joints are simulated to investigate the application of the PIM with the modified fluid flow algorithm. Finally, a fully hydraulic-mechanical–coupled analysis is conducted; the results demonstrate that the proposed model reasonably simulates flow in a generalized fracture network.