This paper gives a brief description of the 3D FEM analysis for a gravity arch dam with consideration of the interaction between dam and complex rock foundation. Results of calculation show the shape and structure of the dam adopted by designer are more reasonable.
Cet article donne une brève description de l"analyse tridlmensionnelle aux elements finis pour un barrage-voûte-poids, en consideration de l"interaction entre le barrage et la fonction rocheuse complexe. Les resultats montrent que la forme et la structure du barrage adoptees par le concepteur sont plus raisonnables.
Eine kurze Beschreibung ueber die 3D FEM Analyse fuer eine grosse Bogengewichtsstaumauer unter beruecksichtigung der Wechselwirkung swischen der staumauer und dem komplizierten Gruendungsfelsen ist in diesem Artikel gebeben worden. Das Ergebnis der Rechnungen zeigte, dass die form und die Strukture der staumauer annimmt von den Konstrukteure mehr vernuenftig ist; -
Geheyan hydropower station being constructed in China is located on, the QingJiang River -- the secondary tributary of the Yangtze River -- of Hubei Province. The project is designed by the "Planning Office of the Yangtze River Basin of the Water Conservancy Ministry of China" in Wuhan. The instal capacity is 1200MW. The type of the dam adopted is concrete gravity-arch dam with the, three center single curve varied section. The maximum height of the dam ia 151 meters, and the length of the crest of the dam body is 653 meters (Fig.1a). Geheyan gravity-arch dam is based on- the complicated rock foundation. On the dam site the river runs nearly from south to north. The-exposed layer are marine facies carbonatite and fragmental rock from Carbrians. The limestones and shale are overlapped, the strike of the layer is about N70°E. The direction of the dip lays to the upstream, and the dip angle falls in between 25 to 30 degrees. There are a lot of weak intercalations with large scales such as 201, 301, 302 and 401, etc. The faults are much developed within the bedrocks, mainly two groups of NNW and NNE both with steep dip angles, where the faults of F10, F12 and F4 in group abound, distribute along the river with strong karst erosion. Fig. 1b gives the general situation of the geological conditions of the dam foundation. Considering the non-symmetry of the valleys shape, the complicated geological condition of the bedrock and the unfavourable rock properties particularly on the upper part of the left bank, the designers proposed a series of measures as follows:
A large concrete gravity abutment on the left bank.
The dam body are divided into 30 dam sections during construction, afterwards only the lower parts of dam sections will be integrated by grouting. By means of this measure, the type of the structure of the Geheyan dam is peculiar. The upper part of the dam consisting of the gravity dam segments works like a gravity dam which is founded on the lower part of dam body being, below the grouting elevation and working as a real gravity arch dam.
The gradual elevating of the grouting level of the dam body reaches as high as 180m on the central part of the dam in order to improve the stress and deformation states. This scheme adopted in design is called as structure scheme I. As the contrasting analysis scheme II with the grouting elevation of 150m on the central part is also taken into account, shown by the dotted line in Fig. 1a.
