Abstract:
The continuous displacement monitoring is essential for the safety control of large dams. It should
be based on the comparison between numerical model results and monitoring data, e.g. observed
displacements using plumb lines, geodetic methods or, more recently, with GNSS (Global
Navigation Satellite System). For Cabril dam, the case study presented in this paper, no plumb
lines were installed in the central section. Thus, the displacement monitoring in this section is
carried out by classical geodetic methods that do not allow continuous monitoring (only two
observation campaigns per year). So, in this case, the use of GNSS was considered particularly
useful, as it allows continuous monitoring of displacements at the top of the central section. As
Cabril dam presents cracking problems since the first filling, it is important to continuously monitor
several notable points, which includes the point at the top of the central section. The present work
focuses on the validation of the displacements obtained by GNSS, at Cabril dam, using a 3D finite
element model, developed in MATLAB, in which the horizontal cracking at the upper zone is
simulated through joint elements. The 3DFE model was calibrated based on the displacements
observed by plumb lines (in two non-central sections) and by classical geodetic methods,
considering variations in hydrostatic pressure and annual temperature variations. The
displacement evolution observed by plumb lines and geodetic methods were analyzed using
HSCT (Hydrostatic, Seasonal, Creep and other Time effects) separation of effects models, to
facilitate the comparison process between the observed displacements and the numerical results.
In this way, the 3DFE model was firstly calibrated using plumb lines results and then it was used
to validate GNSS measurements.
