Simulation of time-dependent response of jointed rock masses using the 3D DEM-DFN modeling approach

Investigating the mechanical response of jointed rock mass, especially its potential changes over time, is vital for the design of geotechnical structures with a long service lifetime. This article studies time-dependent deformations of jointed rock masses based on the 3D distinct element method (DEM) incorporating discrete fracture networks (DFN). A new 3D creep model for jointed rock masses is developed, emphasizing the structural failure due to the creep sliding of joints while considering the long-term strength and the time-to-failure phenomenon of intact rocks. The creep sliding constitutive model of joints is developed based on Barton's nonlinear strength criterion. First, the model implementation, parameter calibration, and model validations are introduced. Then, a case study of the TAS08 tunnel in A<spacing diaeresis>spo<spacing diaeresis> Hard Rock Laboratory (HRL) in Sweden is presented. A DFN model using field mapping data is constructed using Mofrac. The time-dependent response of the TAS08 tunnel is analyzed using the proposed creep model for jointed rock masses. Based on the simulation results, it show that the proposed approach can effectively simulate the time-dependent deformation of jointed rock masses. The DEM-DFN simulation approach provides a valuable tool for analyzing time-dependent responses of excavations and managing hazards associated with structurally controlled failures.