Investigation of the Hydro-mechanical Response and Entropy-based Probabilistic Damage Constitutive Model of Basalt under Compression

Uniaxial/triaxial compression and scanning/backscattered electron microscopy (SEM/BSEM) tests have been conducted in this study to explore the hydro-mechanical (H-M) response and failure mechanism of basalt from Baihetan hydropower station in China. The experimental findings show that the characteristic strengths, deformation behavior, and failure modes of basalt are greatly influenced by confining and pore pressures. Observations from SEM/BSEM tests reveal that the failure mode is due to the development and growth of intergranular/transgranular microcracks. Under H-M loading conditions, the permeability evolution of basalt exhibits nonlinear and distinct characteristics. Additionally, the permeability evolution and failure mode of basalt under the influence of both confining and pore pressures have been discussed. To further describe the H-M response of rocks under loading, continuum damage mechanics theory, in conjunction with strain equivalence and effective stress principles, has been used to establish an entropy distribution-based probabilistic damage constitutive model. To validate the model, the theoretical results have been compared with those obtained from experiments for basalt and other quasi-brittle rock-like materials. The outcome of this study has implications for the engineering design and safety evaluation for structures that lie within rock masses vulnerable to H-M coupling disasters.