Combining constitutive model of saturated fissured rock mass based on engineering mixture theory

In order to analyze the deformation and stability of saturated rock engineering theoretically and numerically, it is necessary to establish a constitutive model of saturated fissured rock mass. Based on engineering mixture theory, the strain of saturated porous medium was divided into skeleton strain and solid matrix strain and fluid matrix strain. The constitutive theory in terms of potential functions was built for saturated porous medium through the homogeneous response principle. The constitutive rules were proposed that skeleton strain was determined by Terzaghi effective stress and solid matrix strain was determined by solid matrix stress and the volumetric strain of fluid matrix was determined by the pressure of fissured pore. According to the classical rock mechanics, the saturated fissured rock mass was regarded as a saturated porous media with fissured pore, and the combining constitutive model was achieved for saturated fissured rock mass. Case analyses show that the combing model of saturated fissured rock mass obtained from the theory of this paper can reasonably take into account the uplift pressure of fissured fluid. It has relatively small coefficient values of pore pressure and anisotropic mechanical features. The combing model of saturated fissured rock mass can be used to study the solid-fluid coupling engineering properties of surrounding fissured rock in the excavation process of channel tunnel. © 2020, China Water Power Press. All right reserved.