Considering the relationship between strain and pressure of solid in the saturated fractured porous rock mass, a new constitutive model was developed to enhance the theoretical foundation for determining the mechanical parameter values of the model. Within the framework of mixture theory, the solid volumetric strain was decomposed into the volumetric strain of fractured skeleton, porous skeleton, and rock material according to the deformation characteristics. Assuming the strain only depended on the conjugate stress in the energy equation, a constitutive model of saturated fractured porous rock mass was developed by the free-energy potential function, and a method for determining the values of mechanical parameters was derived according to the mechanical meaning of the model. The governing equations for fluid-solid coupling were deduced using Darcy’s law. The analysis of the one-dimensional consolidation case showed that, compared with previous parameter value methods, the initial fluid pressure calculated using the parameters determined in the derived method was lower, the initial settlement was larger, and the dissipation of pore excess pressure lagged behind the fracture excess pressure. The sensitivity analysis of the parameters showed that increasing the permeability coefficient ratio greatly improved the consolidation rate of the rock mass while increasing the shape factor had little impact on the dissipation of fracture excess pressure and rock mass settlement.
Yayuan HU,Fei YE. Constitutive model of saturated fractured porous rock mass based on mixture theory. Journal of ZheJiang University (Engineering Science), 2024, 58(7): 1446-1456.
Tab.3Parameters of saturated fractured porous rock mass
Fig.3Fracture and pore excess pressure dissipation for different parameter determination methods
Fig.4Consolidation settlement for different parameter determination methods
Fig.5Diagram of fracture and pore excess pressure dissipation for different permeability coefficient ratios
Fig.6Diagram of consolidation settlement for different permeability coefficient ratios
Fig.7Diagram of fracture and pore excess pressure dissipation for different shape factors
Fig.8Diagram of consolidation settlement for different shape factors
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