A mathematical model for simulating the interaction between underground water flow and mechanical behaviour of the system is used for Izvorul Muntelui concrete dam case. This dam with 126 m maximum height was comissioned in 1961. The data concerning uplift pressures on dam foundation and seepage through foundation versus reservoir hydrostatic levels are used for the back analysis of the dam-foundation system behaviour. In this model corrected according to in situ recorded data are analysed in the second stage different variants concerning grout curtain inclining in order to find out the optimum angle. The optimum variant is selected in compliance with the most favourable effective stress state. The analysis points out, an inclining of 15° of the grout curtain versus vertical direction is recommended.
II s'agit de l'utilisation d'un modèle math, pour simuler l'interaction des l'eaux d'infiltration avec comportement mecanique du systhème aplique à la situation concrete du barrage en beton d'Izvorul Muntelui. D'une hauteur maximum de 126 m, le barrage a ete acheve en 1961. Les donnees employees dans Ie post-calcul du comportement du systhème barrage- -foundation et les debits d'infiltration corespondent aux diverses niveaux de l'eau dans Ie reservoir. Dans la deuxiême partie du papier sont etudiees plusieures variantes pour l'angle d'inclinaison du voile d' etanchement chercheant la valeur optimum, en employant le modèle corrige en concordance avec les enregistrements "in situ". La variante optimum est etablie en concordance avec l'etat d'effort effectif Ie plus favorable. L'etude conseille l'employ de la valeur de 15° par rapport de la verticale, comme optimum pour l'angle de l'inclinaison du voile d'etanchement.
Die Thematik besteht aus einem mathematischen Modell fuer die Simulierung des Zusammenwirkens des Grundwassers und mechanischen Verhatten des Systems fuer den betonentstehenden Izvorul Muntelui Damm.1961 ist der 126 m hochen vevor erwahnten Damm befertigt. Die Daten ueber den hochen Druck auf der Gruendung und ueber die Durchlassigkeit der Gruendung Werden fuer die Analyse des Damm-Gruendung System verwendet. Der zweite Schritt der Analyse des mit dem in situ korrigierten Daten Systems besteht aus der Optimierung des Winkels der Dichtungsbodeninjektion. Der optimale Winkel wird im Verbindung mit dem guenstigsten efektiven Level des Stresses im Untergrund gewahlt. Eine von ungefahr 15° Schrage von der lotrechten Direktion kann beruecksichtig sein.
The mechanical behaviour of a dam foundation system is strongly influenced by underground water flow from reservoir to downstream. The mater seepage, in the rock mass joints and cracks affects the inter-granular state of equilibrium. Many types of fractured rock mass can be considered as porous media in compliance with the nature, geometry and distribution of the fractures which divide the rock mass (Louis, Dessenne, Feuga, 1977). A close interaction exists between water seepage and mechanical behaviour of the system: the flow influences the state of stress, which in turn modifies the permeability coefficients of the rock mass. The effects of the water seepage, especially by uplift pressures on dam foundation as well as seepage forces are of utmost importance for dam safety (Bourdarot, 1992). Izvorul Muntelui Dam is an important concrete gravity dam from Romania, comissioned in 1961. The maximum height of the dam is 126 m and the crest length 435 m (Fig. 1). The dam's foundation consists of gritstones of Tarcau, layered and with clayer schist insertions. Also, two networks of drainage drillings were carried out downstream of the grout curtain, (Popovici, Popescu, 1992). During over 30 years of the Izvorul Muntelui dam operation a lot of monitoring data have been collected. They were very useful for a better understanding of the dam-foundation system behaviour.