A Multiphysics Coupled Interacting Fault System Dynamics Simulator

PANDAS, a novel finite element and/or Lattice Boltzmann method (FEM/LBM) based software has been developed and successfully applied for simulating highly coupled geomechanical-fluid flow-thermal-chemical reaction systems involving heterogeneously fractured - porous geomaterials to address key scientific and technological challenges in the relevant geo-science and -engineering disciplines across different scales spanning from the pore to the lab and filed scale. Currently, it includes six key components (Figure 1): Pandas/Pre, ESyS_Crustal, Pandas/Thermo, Pandas/Fluid, Pandas/LBM and Pandas/Post.

This presentation will focus on Pandas/ESyS_Crustal, a coupled FEM based module developed for the interacting fault system simulation. It employs the adaptive static/dynamic algorithm to simulate the dynamics and evolution of interacting fault systems and processes, in which several dynamic phenomena related with stick-slip instability along the faults need to be taken into account, i.e. (a) slow quasi-static stress accumulation, (b) rapid dynamic rupture, (c) wave propagation, and (d) corresponding stress redistribution due to the energy release along the multiple fault boundaries. Especially, to investigate the multiphysical coupled deformation and faulting behaviors, besides of the material constitutive equations of thermal-geomechanical coupled saturated porous media, an unified friction constitutive equation is also deduced to describe the various affecting factors (i.e. motion state, slip velocity and displacement, contact force, temperature and pore pressure) based on the review of the related research issues and outcomes, and then implemented to PANDAS and validated through different application cases. All these are needed to better describe rupture/microseismicity/earthquake related phenomena with successful applications in natural and/or induced earthquakes (e.g. Fault systems in Sumatra, Southern California, Chuan-Dian region of China (Wenchuan) and Southern Australia), reservoir engineering, hydraulic fracturing and slope stability problems.