Abstract:
Most gravity dam failures occur due to sliding along the dam/foundation interface, rock
mass discontinuities, or rock mass layers of lower strength. The possibility of sliding of a
dam is usually evaluated based on simplified limit equilibrium techniques. In this study an
explicit time-stepping small displacement algorithm, Parmac2D-Fflow, is used to assess the
safety of gravity dams. This algorithm is based on a discrete representation of discontinuities,
simulates the hydromechanical interaction, and considers softening constitutive laws that
are closer to the actual behaviour of the dam/foundation interface. Seepage flow along
the dam/foundation interface is only allowed to occur after contact failure, making it
possible to model a coupled propagation failure along the dam/foundation interface due
to a hypothetical dam overtopping scenario. For two gravity dams with different heights,
the numerical results predicted with a coupled/fracture propagation model are compared
with those obtained with a coupled/fully fractured model and with an uncoupled analysis.
The results presented highlight the relevance of considering a coupled hydro-mechanical
model for dam safety analysis and show that with a coupled-fracture propagation model
slightly higher safety factors are predicted.
