Construction and experimental verification of a damage constitutive model of rocks under uniaxial compression considering seepage pressure

The construction of tunnels and underground projects in a water abundance environment is subjected to increasingly frequent construction accidents arising from the surrounding rock instability caused by groundwater infiltration. Therefore, establishing a damage constitutive model of rocks under uniaxial compression while considering seepage pressure is of great significance for guiding field construction. To characterize the stress-strain relationships in the process of uniaxial compression damage of rocks, this study introduced concepts such as the deformation model of porous rocks, pore aspect ratio, and self-consistent model and theories such as hydrochemical damage and Weibull distribution-based statistical damage into the original constitutive models of rocks while considering the influence of seepage pressure on the modulus of elasticity of rocks. Accordingly, it determined the damage constitutive models of rocks in different stages, elaborated the methods for determining the crack closure stress and damage threshold of rocks, and then established the constitutive equation applicable to the whole uniaxial compression process of rocks under different seepage pressures. As shown by the comparison between the theoretical curves derived from the constitutive model constructed in this study, the actual curves obtained from the uniaxial compression tests of tuffs, and the theoretical curves from relevant literature, the constitutive model constructed in this study represented accurate stress-strain curves of the whole compression process of rocks and, thus, is rational and highly applicable.