Triaxial Rheological Experiments and Rheological Constitutive of Mudstone under Hydro-Mechanical Coupling State

Rheological experiments and the constitutive research on mudstone under hydro-mechanical coupling plays an important role in long-term stability analysis of geotechnical engineering. The rock's temperature, stress, seepage coupling triaxial rheological experiment device was used on mudstone under the hydro-mechanical coupling state and dry state respectively, and their ruptured sections were scanned by electron microscopy after rheological experiments. The results show the follows: (1) The number of mutations in the map of mudstone strain-time under hydro-mechanical coupling is significantly more than that under dry state, which means the osmotic pressure has strong damage effect on mudstone. (2) The axial strain, hoop strain and volume strain of mudstone under the hydro-mechanical coupling state are greater than those under dry state because of the action of osmotic pressure. The stress of mudstone under the hydro-mechanical coupling state when rheological damage occurs is 66.7% of that of dry state, and osmotic pressure has obvious weakening effect on rock strength. (3) The rock's strength reduces faster under the effect of hydro-mechanical coupling by comparison with mesoscopic fracture characteristics of mudstone. (4) The mudstone's rheological model is predicted by results of the test, the modified K-B model was adopted to describe the mudstone rheological deformation behavior, and the fitting results show that the modified K-B model can well simulate the whole process of the mudstone rheological deformation behavior under the two states, and the constitutive model parameter values of the rheological deformation were obtained, which lay solid foundation for long-term rock mass deformation research under the hydro-mechanical coupling.