STABILITY ANALYSIS OF MIDDLE AWASH MULTIPURPOSE DAM BY INTRODUCING INCLINED CLAY CORE

Abstract

Earth rock fill dam with inclined core geometry is well exercised practice in most countries and this type of core arrangement has its own advantage if implemented on the right site condition, however this experience has not been exercised in our country so far. This thesis will present stability analysis of earth rock fill dam with an inclined core geometry which is proposed as an alternative design option for middle Awash dam project. The dam was designed by Ethiopian Construction Design and Supervision Works Corporation in 2016 as a rock fill dam with vertical clay core. The core geometry has been changed from vertical to inclined arrangement in this study and all analysis has been conducted and compared with the original design. The new dam geometry was fixed and checked for static loading condition and same cross section has been used for dynamic analysis. The analysis has been carried out with numerical modeling computer based software called GEO-SLOPE 2007. Based on computation, the flux through the dam has been found to be 0.0057 m3 /sec. A factory of safety of 1.72 for downstream slope during steady state, 1.464 during sudden draw down and 1.225 of downstream slope during earthquake are among the results found. The permanent deformation of the dam after earthquake, 0.803 m is also within the allowable limit. The analysis result shows that the water tightness of the dam, stability of the embankment slope and deformation of the embankment with and without earthquake has never been compromised and even the alternative design proposed in this thesis has performed in a better way for some loading conditions like downstream slope at steady state, construction stage and during dynamic loading. In addition, the revised section found to be significantly economical as compare to the original design (vertical clay core)