Abstract:
Evaluation of the sliding stability of concrete dams requires the use of numerical tools not
only able to simulate the coupled hydromechanical behavior but also able to adequately represent the
foundation discontinuities and the specific features of dam foundations. The formulation of a threedimensional (3D) small displacement finite element model based on interface elements to simulate
the discontinuities is presented. In this model, the hydraulic behavior is simulated assuming that the
water flow occurs only along channels located at the edges of the triangular interface elements that
simulate the discontinuities. The model is used to perform coupled hydromechanical analysis of a
large arch-gravity dam and to assess safety against dam base sliding, assuming different constitutive
models at the dam/foundation interface and two different approaches: (i) strength reduction method
and (ii) amplification of the hydrostatic pressure, assuming an increase in the reservoir level. The
present study shows that consistent results are obtained with the proposed numerical model and
that stability analysis should preferably be carried out using the method of increasing the hydrostatic
pressure and the corresponding uplift pressures, as this methodology leads to significantly lower
safety factors.
