Finite element simulation and analysis of frictional dynamic behavior of fault system

Most large earthquakes occurred along pre-existing faults and are widely regarded as a kind of frictional instability behavior on faults. It is of great significance to study the interacting fault system involving frictional instability dynamics for numerical prediction of earthquakes. Firstly, the related progress on finite element simulation of interacting fault dynamics is reviewed, especially the treatment methods of friction dynamic behavior and the contact interface. The characteristics of different time integration schemes in the finite element simulation calculation are comprehensively compared and analyzed. The non-convergence issue is discussed due to high nonlinearity in simulating fault friction instability using the conventional finite element method. Considering the relevant differences and difficulties as above, the R-minimum strategy based adaptive control scheme of time step size, its related finite element algorithm and software are proposed and briefly introduced, which takes into account the advantages of static implicit and dynamic explicit, and transforms the unstable implicit iterative calculation into the explicit one; At the same time, using Coulomb's friction criteria together with the rate and state-dependent friction law, the three-dimensional nonlinear contact friction dynamic behavior between deformable bodies are simulated by node-to-point arbitrary contact element. The relevant successful application examples are summarized. In addition, to construct a finite element mesh model with complex faults, the appropriate finite element mesh generation algorithms are reviewed. The application presents our recently developed image-based mesh generation methods of quadrilateral and hexahedral meshes subjected to complex fault constraints. It is simulated and analyzed using our R-minimum strategy-based finite element algorithm and code to investigate the fault friction behavior and its effects on the fault system to demonstrate its capability and usefulness.