Assessment of the filtration through earth dams when changing their parameters using the Z_SOIL software

Abstract

Introduction: In the Arab Republic of Egypt (ARE), earth dams are widely used to prevent flooding. All earth dams of reservoirs are typically characterised by water filtration through their embankment dams, bases, and adjoining sides of the valley, which form an artificial aquifer. A quantitative assessment of this process is a serious hydrogeological task, and it is also necessary to solve many hydrological and geoecological problems. Methodology: The Z-SOIL program was used for the numerical solution of the issue. It is based on the finite element method. The program is designed for the simulation of non-steady state filtration with the possibility of changing water level, the size of the filtering object, and the properties of its soils. At the beginning of the study, an experiment simulating filtration and soil permeability was carried out on a physical model of a dam in the laboratory. Then the numerical geofiltration simulation was calibrated comparing the simulation and the experimental data. Finally, the impact of changes in the dam geometry on the water level in the reservoir was assessed. Results and discussion: The results of the numerical simulation are in good agreement with the experimental data. It was found that as the width of the dam crest and the height of its base increased, the water level in the reservoir decreased due to the filtration through the dam with a maximum change in time to 0.3% and 0.26%, respectively. Conclusions: Using the degree of saturation of the rocks and the pressure at the upper pool of the reservoir as variables, the Z-SOIL model allows for the simulation of non-steady filtration through an earth dam. Comparison of numerical data with the experimental results shows that the described simulation method allows us to simulate quite accurately the changes in the surface level inside the dam (embankment dam) over time under real conditions. The results are coherent with the practice of operating sand dams and allow for a preliminary assessment of filtration through a dam and selection of the parameters for its construction.