| A general multidimensional numerical model was developed for simulating the saturated-unsaturated fluid flow in deformable porous and fractured media by fully coupling the fluid flow and deformation fields, which are explicitly and implicitly interlinked. The explicit coupling between these two fields was achieved by simultaneously solving the mathematical equations governing fluid flow and media deformation. The implicit coupling was accomplished by considering the effects of both unsaturated flow and solid skeleton (medium) deformation on the hydraulic parameters such as water content and hydraulic conductivity. The implicit coupling caused by the medium deformation is important because it may produce the heterogeneity and anisotropy of porosity and hydraulic conductivity and consequently influence the fluid flow field even though the medium is fully saturated. The porous medium (PM) and fractured medium (FM) models were presented to consider and explain such deformation-dependencies of porosity and saturated hydraulic conductivity for porous media and fractured media, respectively. The mathematical governing equations and the PM and FM models were implemented in a multidimensional numerical code, named COWADE123D, by using the Galerkin finite element method. To verify the code, loading and aquifer pumping problems which have known analytical solutions were examined without considering the deformation-dependencies of porosity and saturated hydraulic conductivity. In such cases, the numerical simulation results showed extremely good agreement between the analytical and numerical solutions in all the verification examples considered. When the deformation-dependencies of porosity and saturated hydraulic conductivity were considered by the PM or FM model, the simulation results showed significantly delayed or somewhat deviated trends from those of the preceding verification examples. The verified code was applied to several hypothetical problems in which the fully coupled subsurface fluid flow and solid skeleton deformation process may play an important role in controlling the system behaviors. The simulation results show that the unsaturated flow, the heterogeneity, and the anisotropy have their own importances not only in the fluid flow field but also in the solid skeleton deformation field. |
