A fault activation-shearing-sliding peridynamic model exploring the role of static and kinetic frictional contacts

Understanding fault dynamics is essential for comprehending the underlying mechanisms of seismic events. This study introduces a novel fault activation-shearing-sliding model within a peridynamic (PD) framework, characterized by distinctly defined static and kinetic frictional behaviors. Static friction bonds are developed to sustain normal forces perpendicular to the fault plane and to manage tangential frictional forces along the fault's geometry. The failure of these bonds is directly linked to fault activation, while the ensuing sliding phase is governed by a short-range kinetic friction model. Additionally, an adaptive identification method is proposed to accurately determine local unit normal vectors on arbitrarily shaped contact surfaces. The effectiveness and applicability of the model are validated through fault activation and plate sliding friction tests. The model is further utilized to investigate the effects of local geometry, roughness, and friction coefficients on fault behavior, with comparisons to experimental results. Observations indicate that the dominant factors influencing fault shear resistance vary across stages, primarily involving static friction during activation, compaction deformation during shearing, and kinetic friction during sliding. When shear resistance is primarily governed by friction, it exhibits heightened sensitivity to various shear forces, including those from indirect loading disturbances.