Mechanical Behavior and Damage Constitutive Model of Rock Subjected to Water-Weakening Effect and Uniaxial Loading

Water-weakening effect is one of the most important causes triggering large deformation and failure of soft-rock engineering; however, few studies have paid attention to damage evolution and constitutive relationship of rock in water-weakening process. In this paper, laboratory tests are first carried out to estimate the evolution of mechanical properties along with changes of immersion time for shale samples. Then with the aid of X-ray diffraction and scanning electron microscope, mechanism of parameter degradation for shale under immersion conditions is investigated from the microscopic perspective. Based on the generalized strain equivalent principle and the theory of statistical microscopic damage mechanics, a damage constitutive model of rock subjected to water-weakening effect and uniaxial loading is established by considering the influence of void-compression stage, and the proposed model is verified to be in good agreement with the experiment results. This paper provides an effective approach to analyze the constitutive relationship of rock subjected to water-weakening effect and uniaxial loading.