Analyse numérique du comportement sismique d'un barrage en enrochement avec un noyau en béton bitumineux

Since half a century, a new kind of dam has been developed. This new type of dam uses a thin core asphalt concrete (about 1 m thick) instead of a traditional low-permeable material, such as clay, supported by compacted granular materials and then rockfill. These dams are called asphalt core rockfill dams (ACRD). There are currently 90 ACRD's in operation around the world and nearly 45 of these dams are being designed or are under construction. The thin asphalt concrete core is completely impermeable, flexible and capable of self-healing if fissured (to a certain degree). Thanks to these characteristics, the general comportment of an ACRD during its construction, reservoir filling and seismic loading is quite satisfactory. In addition, it allows for the construction of the dam under poor climatic conditions, such as rain, and in an area where the quality or the quantity of impervious materials are limited. Most of ACRDs can be found in Europe and in China. There is only one ACRD in South America and two in North America. The main goal of this study it is to evaluate the seismic performance of a representative ACRD by means of dynamic numerical analysis using a hyperbolic stress-strain model based on Duncan and Chang (1970) for simulate the granular and rockfill materials and takes into consideration hysteretic damping and shear modulus reduction during the dynamic analysis. The analysis was conducted using PLAXIS 2011.02 2D and considered the effect of reservoir filling and dynamic loading based on typical and extreme earthquakes on the east and west coasts of North America. Special attention was given to the deformation of the asphaltic core. This analysis was compared to the results of traditional seismic analysis as the pseudostatic method and the permanent displacements method.