Modeling transient groundwater flow under dikes and DAMS for stability assessment

Dikes and dams protect the land from flooding by mitigating high water levels. However, water penetrating the dike and the subsoil during high water periods reduces the strength of the dike due to the increase in pore pressure. Moreover, the raise in hydraulic head in deeper layers may lead to uplift of the top layer at the polder side of the dike, and finally an increase in the potential head gradient might lead to an internal erosion process called piping. To assess these effects it is important to have an adequate knowledge of the pore water pressure field. At present, pore water pressure fields are often obtained by solving the flow problem. This approach provides a computationally efficient method and requires less soil parameters than needed for solving the fully coupled flow-deformation problem. However, the flow formulation is not capable of correctly simulating the generation of pore water pressure due to hydraulic loading of the subsurface. This paper presents a numerical model for solving Biot's problem and compares the solution of the flow-deformation formulation to the solution of the flow formulation.