Evaluation of Seepage and Slope Stability of the Embankment Dam: (A case of Grindeho Dam)

Abstract

Embankment dam failure may occur due to different reasons such as structural instability conditions, hydraulic conditions, seepage through the dam body and foundation. The determination of factor of safety for the dam slope stability, under different cases of operations, is vital to ascertain the dam overall safety. In this thesis, Finite Element modeling is employed for simulating seepage and slope stability analysis of earth dam problems via GeoStudio software. The model is verified, and then it is employed to analyze seepage and stability of Grindeho Dam. Three different cases of operation are considered; end of construction before filling the reservoir, steady state seepage and rapid drawdown of the reservoir. Four major analytical methods there used to assess the stability of the dam side slopes; Morgenstern-Price, Bishop, Janbu, and Spencer. Benchmark safety regulation criteria (United State army of Corps Engineers and British dam society) are obeyed. Additionally slope stability determined by simple/manually calculation by simplified Bishop Method; finally the result was compared with slope/w software result. The results of the analysis presented in this paper confirm the safety of Grindeho dam against combined seepage and slope stability under all cases of operation. The result of stability analysis performed showed that all parts of the dam are safe within the prescribed rang of factors of safety for the possible all loading and operation cases. But all the critical slip surfaces pass through the dam shell which indicates that this zone represents the weaker zone and it needs spatial attention.