Damage-tensor-based nondimensional parameters governing secondary faulting behavior

Two nondimensional parameters associated with secondary faulting are found in terms of damage tensor. From an analytical viewpoint, it can be concluded that these two nondimensional parameters govern the system behavior completely if a nonlinear interaction between damage evolution and the medium deformation is relatively small. One, C, determines size of area where secondary faulting occurs, and the other one, γ, governs eigenvalue ratio, which was introduced for two-dimensional problem in a previous study of the author and is now expanded to three-dimensional problem, and qualitative behaviors of secondary faulting. Smaller γ tends to produce fault rock pulverization, while larger γ has tendency of inducing branch development. Intermediate cases for γ is related to their mixed occurrence. Actually, the nonlinear interaction is confirmed to be negligible over whole ranges of parameters associated with damage evolution. Fault rock pulverization and branch development are understood systematically as secondary faulting, including the case where they occur simultaneously.