Hydromechanical modeling of solid deformation and fluid flow in the transversely isotropic fissured rocks
Computers and Geotechnics, 128:103812, 2020.
Summary
An anisotropic double-porosity elastoplastic formulation is presented for sedimentary rocks that contain both matrix pores and fissures. The model couples deformation of the solid skeleton with fluid movement through the two pore systems, while accounting for the directional behavior associated with bedding. A new implicit stress-update algorithm handles the loss of coaxiality between trial and corrected stress states and computes the updated effective stress, internal variables, and consistent tangent operator. A uniaxial-strain calculation supplies a benchmark for this procedure. Three-dimensional material-point simulations then use triaxial test data to calibrate the constitutive parameters and illustrate strain softening. Finally, boundary-value examples examine how the assumed flow behavior and solid constitutive response influence the overall hydromechanical solution. The work provides a numerical framework for studying coupled processes in transversely isotropic fissured rocks.