Concrete buttress dams are the most common type of dam in Sweden. The consequences of a potential failure are severe, which emphasizes the importance of high-level dam safety. At the time of writing, the current method for the design and evaluation of the stability constitutes a 2D analysis, with the separation of one monolith on a flat surface. Previous studies have indicated that the current evaluation method neglects important 3D effects and underscores the importance of including these effects. Therefore, this degree project aimed to analyze the impact of these effects on global and local stability. The 3D effects of interest in this thesis were the interaction between monoliths and the influence of a cross-valley inclined topography.

This was achieved by first, validating the method approach with available results from physical model tests. Several FE models were produced and compared to the data from the physical model tests. Later, a generic dam with different lengths and different topography inclinations was simulated as a parametric study. The generic dam was inspired by a real Swedish concrete buttress dam. Push-over failure analyses were performed using finite element models so that the impact from 3D effects could be analyzed.

The result of the global analysis indicated that the 3D effects have an impact on the stability assessment. The cross-valley inclination of the topography caused the monoliths to be pushed together, creating a stabilizing interlocking effect. This effect was increased with an increased inclination. The shorter dam with a more inclined topography could therefore withstand a larger load compared to the longer dam with a less inclined topography. The local analysis showed that the inclusion of topography inclination resulted in a reduction of the safety factor. However, to enhance the reliability of the results and extend the study, further research is recommended.