The hydro-mechanical (HM) behavior of the engineered barrier system (EBS) is significant for the design of the underground radioactive waste disposal facilities and for its long-term safety. The EBS is subjected to environmental processes, such as: changes in moisture content due to the water uptake from the host rock and changes in stresses due to the physical confinement of the bentonite under such hydration conditions. When subjected to hydration, the bentonite exhibits a strong swelling response that significantly affects the hydraulic and mechanical behavior of the material. In order to understand and quantify the main HM processes that take place in the EBS and to minimize the in-situ uncertainties, MGR’s laboratory hydration tests have been carried out by CIEMAT (Madrid, Spain). The experiments consist in the combined use of highly compacted blocks and pellets bentonite subjected to hydration to simulate the EBS concept. The observations gathered in the laboratory tests have provided the opportunity to examine the HM response of micro- and macrostructure in an integrated manner. The hydration laboratory tests have been modelled through a fully coupled double structure approach that has been implemented in a finite element code. The formulation represents the expansive material as two overlapped structural media coupled through a strain mechanism relating the irreversible changes in the macrostructure to the volumetric deformations occurring in the microstructure. Numerical analyses have been carried out and have proved the capability of the numerical formulation to provide adequate predictive capacity. The paper presents an interpretation and comparison between the MGR’s results and numerical modelling showing the predictive power of the Double Porosity Model (DPM).