A Damage Constitutive Model of Red Sandstone under Coupling of Wet-Dry Cycles and Impact Load

Figure 1

Superposition of coupling damage variable. Samples subject to (a) both macroscopic and mesoscopic damage, (b) only mesoscopic damage, (c) only macroscopic damage, and (d) and free of any damage. The damage variable, strain, and elastic modulus under stress are D₁₂, D₁, D₂, and D₀; ɛ₁₂, ɛ₁, ɛ₂, and ɛ₀; and E₁₂, E₁, E₂, and E₀, respectively.