Simulation et analyse du phénomène d'infiltration dans les barrages en terre : cas du barrage de Fontaine des Gazelles (w. Biskra)

Abstract

Water, one of the key sectors of sustainable development where progress is still possible thanks to the existing resources and technologies currently at our disposal. The sustainable development of humanity depends on the supply of water. It is estimated that more than a third of food production depends on irrigation. As such, the Algerian state has attached great importance to investments in this field, building more than eighty large dams with large transfers. However, these dams are often confronted with technical or natural problems, with considerable amounts of water being lost each year due to infiltration. These infiltrations can put the safety of these dams in critical states. The zoned fountain of gazelle dam located in Biskra in south-eastern Algeria, has suffered since 2004 from the problem of infiltration on its right bank following an early filling of its reservoir. The piezometry under the gallery is a sign of significant percolation likely to degrade the watertightness veil. An abnormal pressure disturbance was observed in the P3 piezometer located on the downstream face in accordance with leaks at the downstream toe of the dike. The objective of the present thesis is firstly to detect the origin of these infiltrations by the method of isotopic geochemistry with stable isotopes (2 H, 18 O) after having analyzed and processed all the dam piezometric data. Secondly, simulate the infiltration problem before and after the injection solution with a fine cement grout in order to treat the effect of the fault under the dam foundation. The results obtained show that for the three auscultation profiles with the exception of the P3 piezometer, the hydraulic gradient is moderate, and the abnormal increase of the latter proves the percolation of the water. Furthermore, the source of the infiltration water comes from the reservoir, and that the simulation of the coupled hydromechanical (HM) problem using the numerical code of Code Bright.V13, gives logical, significant results and compares with those measured with very acceptable errors (MAPE= 2.41% and R2= 0.832). The simulation with the proposed solution can effectively reduce the pressure of the P3 piezometer by 65% and put the dam in complete safety.