Displacement based coupled model for unconfined seepage problems applied to the Gasset Dam (Ciudad Real, Spain)

The present work shows the application of a new methodology, to find out the free surface inside earth fill dams under steady flow conditions, to a real field case: the Gasset Dam, in Ciudad Real, Spain. An accurate and fast computation of the free surface is of paramount importance, since it is a previous and necessary step for evaluating the safety of an earth dam in terms of its stress–strain behavior. This new methodology is based on a coupled numerical model formulated in terms of displacements (so called u–w formulation) instead of a more usual approach of water heads. The developed general code has been previously validated using several theoretical seepage problems through porous media. The selected field case is an earth dam built a century ago, which has been subjected to several rehabilitation works since then. Hence, it is a very irregular and nonhomogeneous dam. The comparison of computations and real field measurements, in terms of the free surface location and the total discharge through the dam under steady conditions, is presented in this paper, demonstrating the accuracy and applicability of this formulation to this kind of problems.

► A new methodology for computing free surfaces in earth dam is tested.
► The methodology is formulated in terms of water flow displacements.
► A very important, heterogeneous old earth dam in Spain is employed as field case.
► The comparison of computations and field data addresses the accuracy of the method.
► The old pathology of the dam before it was repaired in 1999 has been identified.