PERFORMANCE EVALUATION OF EMBANKMENT DAM AND REMEDIAL MEASURES (CASE OF KESEM EMBANKMENT DAM, AFAR REGION, ETHIOPIA)

Abstract

Safety of earth dams depends on the proper design, construction, and monitoring of actual behavior during the construction and during the operation of the structure. The geotechnical and geodetic monitoring besides providing a warning system in case of an abnormal behavior of the dam may be used as a tool for a verification of design parameters where geotechnical parameters are of the highest importance by comparing results of monitoring measurements with a prediction (deterministic). Geostudio software is one of geotechnical program that is based on the finite element and can consider analysis like stress-strain, seepage, slope stability, dynamic analysis and also fast water drop in reservoir by assume different mesh size. In this research geostudio has been used to analysis the stability (seepage, slope stability and stress deformation) of kesem rock fill dam. In addition to stability the seepage source has been identified using daily Electrical conductivity and temperature of the reservoir, hot spring, ground water, right and left abutment seeped water data. The Result show that average flow rate of leakage under the different mesh size for kesem dam equal to 0.0159m 3 /s for the entire length of the dam and Slope/W software is used under different conditions to evaluate slope stability Analyzes for each state and each slope with Bishop, Janbu, ordinary method of slides and Morgenstern methods is calculated and compared with the minimum acceptable safety factor provided from United States army of Corps. In the other hand the mechanical behavior of kesem rock fill was evaluated at the end of construction and a two dimensional numerical analysis was conducted based on a finite element method on the largest cross section of the dam.The data recorded by the instruments located in the largest cross-section were compared with the results of the numerical analysis at the place of instruments. The vertical settlement and horizontal displacment was the parameters used for evaluating the dam behavior at the end of construction and the results showed that the settlements obtained from the numerical analysis were in reasonable agreement with the data recorded by the instruments.