EXPERIMENTAL AND NUMERICAL STUDY OF THE INFILTRATION PHENOMENA IN A COMPACTED CLAY DESIGNED FOR THE DEPOSIT OF SHORT-PERIOD RADIOACTIVE-WASTES

An unsaturated compacted silt bed could be included in the typical cov er scheme of a radioactive waste deposit. The analysis of general laws of unsaturated porous media flows shows the influence of the hydrodyn amic characteristics of the compacted material on the infiltration pro cess. Using analytic relationships which are defined with a few adjust ment parameters, a numerical model was built. Infiltration tests were carried out in large size cells and under varied flow boundary conditi ons. The comparison of the experimental and numerical results allows, on one hand to define the adjustment parameters of the studied materia l and on the other hand to validate the numerical modelling. Using thi s numerical model, the influence of the adjustment parameters, air flo w and boundary conditions on the infiltration kinetics is studied. The parametric model of a thick clayey soil bed for great infiltration ti mes shows a relationship between the initial state of the material (wa ter content. specific density), the ratio of the infiltration flow ove r the permeability of the natural saturated soil and output flow and t he saturated zone into the bed.