Settlement analysis of the Montesinho CFRD

Abstract

Concrete face rockfill dams (CFRDs) are becoming a widely used type of rockfill dam all over the world. Until recently, the design and construction of CFRDs were empirically based primarily on precedent and engineering judgments. Few numerical or analytical methods have been developed to properly evaluate the deformation of CFRDs, which is important for dam safety and for subsequent evaluation of seismic performance. This paper describes the setup of a finite element method (FEM) model for the three dimensional simulation of the construction of Montesinho CFRD and filling of the its reservoir using the Code-Aster code. The prototype of the study is the 36.5 m high Montesinho CFRD, located in the north of Portugal near the Spain border, in the Sabor river in the Montesinho Natural Reserve, witch has been completed in 2016. Settlements are regarded as a key indicator of dam safety. Therefore, the time-dependent settlement behaviour of Montesinho CFRD is studied on the basis of in situ settlement-monitoring records. The monitoring results covered the construction period, the initial filling of the reservoir and 2 years of operation. Two different elastoplastic models (Druker Prager, Cam Clay) were implemented to better model the rockfill materials. The model parameters were calibrated by large-scale triaxial tests, performed on materials used in the dam. The numerical results agree well with in situ monitoring records of dam settlements, allowing to predict the deformation of the dam in the future.