Prediction of Earth Dam Seepage Using a Transient Thermal Finite Element Model

With the majority of the United States Department of Agriculture-Natural Resources Conservation Service (USDA-NRCS)-sponsored earthen dams exceeding their planned service life, seepage is a concern since it is a common failure mechanism among earthen dams as a whole. Seepage occurs when water penetrates a hydraulic barrier to create open pathways, channels, or piping leading to internal erosion or stability issues due to increased effective stress. Due to the complex geometries of these hydraulic structures, time-dependent boundary conditions, and complicated failure analyses, numerical approaches have been used to estimate seepage. However, the existing numerical models are either computationally expensive or assume steady-state conditions. This work develops the framework for using a transient thermal finite element analysis (FEA) model as an analogy to predict transient seepage. The FEA model is compared to a transient analytical model to verify the approach. A sensitivity analysis of the FEA model shows that the time aspect of seepage flow is dependent on the medium, i.e., soil, and not on the fluid properties.

Automated summary

With many USDA-NRCS-sponsored earthen dams exceeding their service life, seepage has become a common concern due to its potential to cause internal erosion or stability issues. Existing numerical models for estimating seepage are either computationally expensive or assume steady-state conditions. This study proposes the use of a transient thermal finite element analysis (FEA) model as an analogy to predict transient seepage, and its accuracy is verified by comparing it with a transient analytical model. A sensitivity analysis demonstrates that the time aspect of seepage flow is dependent on the medium (soil) rather than the fluid properties.