Interface Plastic Constitutive Law With End‐Cap and Structural Model Applied to Geological Faults Behavior

Abstract

AbstractThis paper proposes a framework for the mesoscale modeling of potentially complex fault cores. Such faults cannot be modeled as simple frictional interfaces because they may be thicker and made of several slip surfaces embedded in a material that can contain both grains and broken blocks. Two main aspects are considered here. One, which is the main innovation in the paper, deals with the derivation for the specific rigid‐plastic interface constitutive law which was developed to account for the hardening/softening behavior of highly stressed rocks like in geological faults. The other one deals with the theoretical and numerical study of the response of the structural model in which this constitutive law was implemented. This first structural model was chosen to represent the behavior of faults surrounded by elastic rock masses. The results obtained from this model already illustrate the high potentiality of the proposed interface constitutive law in the context of seismology. When far‐field displacement boundary conditions evolving time are used, different modes of evolution emerge, and transitions happen, from quasi‐static to dynamic or vice versa with timescales extending from tens of years to seconds. The instability domain and the dynamic solution are detailed together with the related energy considerations. An extensive analysis of specific case studies is available in Maury et al., companion paper, in particular as regards the possibility for slow slip events to transition into seismic slip (or vice versa). The implementation of the interface model into more realistic and advanced numerical fault models should offer many perspectives.