Global Frictional Equilibrium via Stochastic, Local Coulomb Frictional Slips

Abstract

A simple quasi-static 2D model simulates the global stress relaxation of fractured rock mass due to local frictional slips • The fractures in the rock mass are stochastically assigned with varying frictional coefficients, representing the system heterogeneity • Global stress evolution of the stochastic case differs from its deterministic counterpart, extending the notion of frictional equilibrium Supporting Information:

How Does In Situ Stress Rotate Within a Fault Zone? Insights From Explicit Modeling of the Frictional, Fractured Rock Mass

“…The fracture constitutive behavior in this study is independent of time, which ignores the significant evolution of fracture deformation with time (Brantut et al, 2013;Scholz, 1968). If time-dependent fracture behavior is considered, it is expected to further promote stress rotation and weaken the rock mass frictional strength in a temporal sense (Zhang & Ma, 2021). In addition, the stress variations and effective elastic property changes in our model can be more pronounced, when further energy dissipation mechanisms are introduced to both the fractures and the matrix.…”

“…In this section, the mechanical behavior of a frictional fracture under plane strain condition (Zhang & Ma, 2021) is extended to include elastic deformation. In particular, a complete constitutive law for the frictional fracture is derived under loading and unloading conditions, respectively, which is used to calculate the fracture-induced stress changes inside the multilayer model in Section 3.…”

“…Therefore, the additional strain in the y-direction contributed by fractures entails the adjustment of strain in the elastic matrix. Equivalently, σ yy should be modified to accommodate the corresponding strain increments (Zhang & Ma, 2021). The interplay between local fracture deformation and specific boundary conditions of the model drives the stress variations in a self-regulated manner.…”

Impoundment‐Associated Hydro‐Mechanical Changes and Regional Seismicity Near the Xiluodu Reservoir, Southwestern China

“…This correlation corroborates the primary control of fault criticality on seismicity occurrence, but there remain some obstacles to predict the regional seismicity evolution. The fault criticality is a conditional scalar index based on the assumed probabilistic distributions of in-situ stress field, fault geometry, and frictional coefficient, which are quite heterogeneous and difficult to constrain (Lund Snee & Zoback, 2018;Ma et al, 2020;Shen et al, 2019;Walsh & Zoback, 2016;Zhang and Ma, 2021). Despite the possible deviation of the assumed parameter distributions from the realistic in-situ conditions, the first-order quantification of fault criticality is rather informative to estimate the faults' susceptibility to reactivation, particularly in the context of nearby reservoir impoundment.…”

Impoundment-associated Hydro-mechanical Changes and Regional Seismicity near the Xiluodu Reservoir, Southwestern China

“…This correlation corroborates the primary control of fault criticality on seismicity occurrence, but there remain some obstacles to predict the regional seismicity evolution. The fault criticality is a conditional scalar index based on the assumed probabilistic distributions of in-situ stress field, fault geometry, and frictional coefficient, which are quite heterogeneous and difficult to constrain (Ma et al, 2020;Shen et al, 2019;Snee & Zoback, 2018;Walsh & Zoback, 2016;Zhang & Ma, 2021). Despite the possible deviation of the assumed parameter distributions from the realistic in-situ conditions, the first-order quantification of fault criticality is rather informative to estimate the faults' susceptibility to reactivation, particularly in the context of nearby reservoir impoundment.…”