Study on the unloading damage constitutive model of sandstone based on hydro-pressure cycle

Abstract

The periodic rise and fall of reservoir water level under hydro-pressure cycle leads to the deterioration of physical and mechanical properties of rock and seriously triggers the instability of the reservoir slope. From the laboratory data and characteristics of the stress–strain curve under different hydraulic cycles, combined with the generalized Hooke’s law, the Weibull distribution theory, and the Hoek–Brown strength criterion, the energy dissipation in the unloading process is assumed as the damage variable, and the unloading damage constitutive model of saturated sandstone under hydro-pressure cycle is established. Under hydro-pressure cycle, the parameters m and F of the constitutive model are gradually decreasing, and the sandstone brittleness and macroscopic strength are gradually weakened. In addition, the scattered energy increases, while plastic deformation slowly plays a dominant role. The comparative analysis shows that the constitutive model fits well with the experimental curves. The damage constitutive equation can be expressed under hydro-pressure cycle. This research can help in the stability analysis of rock slope under the reservoir water in the field.