# Study on Experimental and Constitutive Model of Granite Gneiss under Hydro-Mechanical Properties
###### Abstract  
Permeability, as a critical element in making sure the underground facilities are secure, is a vital consideration in analyzing the rock material seepage. Selecting granite gneiss from underground oil storage as the research sample in this study. Triaxial mechanical property tests under different hydro-mechanical properties were carried out under the rock full-automatic triaxial servo system that controls the application of axial pressure, confining pressure, and seepage pressure. Through experiments carried out, we obtained the rock samples' mechanical properties and permeability in three stages of the stress-strain process. The study shows that the seepage pressure considerably affects granite gneiss strength and deformation parameters under hydro-mechanical properties. On the basis of the same confining pressure, in pace with the growth in seepage pressure, elastic modulus, the deformation modulus, and the peak strength present a prominent decreasing inclination. The derived mechanical parameters are bound up with the stages we divided. This study analyzes and discusses the relationship among the strains and permeability, establishing the granite gneiss hydro-mechanical coupling constitutive model. Verification shows the results in numerical and experimental matches well, indicating that the rock hydro-mechanical properties could be effectively represented by the constitutive model.  
g 2023 13 12130 13 12130 1  
years, domestic and foreign scholars have also achieved a substantial amount of research results on indoor uniaxial or triaxial hydro-mechanical properties tests of rocks using water as the permeable medium [11; 12; 13; 14; 15; 16; 17]. From this research, the rock permeability is mainly with regard to elements, for instance, the strain, stress, fluid, pore pressure, and temperature, with the main research object being rocks with larger pores. The permeability of low-permeability hard rocks is rarely involved. Moreover, previous research mainly centered on the association between permeability and axial strain, with small amounts of research studies detailing the quantitative relationship among circumferential, volumetric strain, and rock permeability [18; 19].  
The rock's mechanical behavior can be represented by the constitutive model on rocks [20]. The constitutive model is an effective way to research the rock coupling characteristics in a water environment. The central research methods include applying empirical equations to test results directly, parallel connections of assorted components, as well as adding nonlinear terms. In view of the elastic-plastic theoretical framework, there were three sorts of rock constitutive models [21; 22; 23]. By simulating the influence of seepage in rocks on their deformation behavior under stress, the permeate influence on the rock's inner stress field can effectively be achieved. By characterizing the internal permeability evolution law of rocks through the deformation behavior under stress, the stress field effect on the seepage field can be achieved, thereby achieving the hydro-mechanical properties of rock. This research is beneficial for considering the study of rock mechanical properties, failure mechanisms, and evolution laws of seepage characteristics under the coupling state of a seepage environment and stress. It also provides a considerable reference for the security and perdurable stability of major national infrastructure items, that is, water conservancy and hydropower engineering, underground energy storage, as well as transportation engineering.