3D Nonlinear Analysis of Atatürk Clay Core Rockfill Dam Considering Settlement Monitoring

Abstract

One of the most important causes of damages in clay core rockfill (CCR) dams is the deterioration of the rockfill material over time and big settlements in the dam body. Therefore, the forecast of the settlements and principal stresses in a CCR dam is extremely important for the safety and future of these important water structures. In this study, changes in the nonlinear behavior of a CCR dam were examined by effects of the various reservoir water heights. Moreover, the geodetic measurements were confirmed with the nonlinear analysis results. Atatürk Dam, which is the largest CCR dam in Turkey, was selected for three-dimensional (3D) nonlinear analyses. First, a 3D finite-difference model of Atatürk Dam was created using the FLAC3D software, which is based on the finite-difference method. A Mohr-Coulomb material model was used for the dam body materials (e.g., clay core, filters, alluvium, rockfill) and foundation for the 3D numerical analyses. Numerical analyses were carried out for five various reservoir water heights: empty reservoir, 50, 100, 153, and 170 m (full reservoir). According to the finite-difference analyses, the effect of various reservoir water heights on the nonlinear behavior of the Atatürk dam was assessed in detail, and how much maximum vertical settlement will occur in the Atatürk Dam body in the future was determined. In addition, principal stresses and horizontal displacements were evaluated for each reservoir condition, and these results were compared with each other. This study demonstrated that as the reservoir water height increased at the upstream side of the dam, the principal stresses and vertical–horizontal deformations occurring in the dam body obviously changed and increased. In the second part of this study, the geodetic vertical settlement results observed by the General Directorate of State Hydraulic Works (DSI) between 1992 and 2013 were presented graphically. These geodetic observation results and numerical analyses were compared in detail, and the geodetic measurement results were confirmed by numerical analysis results.