FAILURE INVESTIGATION OF SAMAKI EARTH DAM By Joyce

Abstract


The design and construction of an earth-fill dam is one of the key challenges in the field of geotechnical engineering. For an earth fill dam thorough investigation of the properties of the available construction materials and foundation condition is a pre requisite before any design process.
This study outlines the causes of failure of earth fill dams which are the most common type of dams. An emphasis has been given to homogenous dams which should be constructed with relatively flat slopes to minimize the risk of failure. Due to lack of suitable clay materials, sometimes the dams are designed as zoned core that is composed of the central impermeable core flanked by more pervious shells.
A failure of earth dam is attributed to the following: hydraulic failure and Geotechnical failure which involves a seepage failure or a structural failure. A dam can fail due to more than one reason since the various modes of failure are linked up in a composite way in the sense that one mode of failure can trigger the other. The causes of earth dam failures were considered with emphasis on failure due to geotechnical reasons. Suggestions are given on how earth dam failures can be minimized in terms of good design practice appropriate construction and improved maintenance culture.
Samaki dam was drained in October 2015(2 years after construction) amidst fears of breaching attributed to the poor condition of the embankment which was evident through visual inspection. It was found out that the failure majorly resulted from inadequate engineering practice which was majorly characterized by inadequate quality construction control. Consequently there was excess seepage, two slides and erosion which led to the unsoundness of the embankment. Suggestions are given on how the failure ought to have been prevented. It was recommended that the embankment should be reconstructed again taking into account the given suggestions.

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