ASSESSMENTS OF SUITABILITY OF CONSTRUCTION MATERIAL WITH SPECIAL EMPHASIS ON FILTER: - THE CASE OF AGUAT WUHA EARTH DAM AT

Abstract

Aguat-wuha dam is an earth fill dam, which is one of the Irrigation Projects undertaken by AWDSE found in South Wello Zone, Sayint Ajibar Woreda. As it was observed, during the construction process the construction material, the filter material in particular, was not properly prepared while placement. This could result in malfunctioning of the filter zone as a because of material poor gradation and contamination. Hence, this work was aimed to evaluate the suitability of construction material especially on filter material assessments. During this research work materials for analysis were taken from the dam which is on construction and filter material samples stored in stoke. The geometrical criteria have been mainly checked using the formulas and recommendations proposed by scholar and standard. In addition to this, the final gradation or grain size distribution of a suitable filter material has been prepared based on the gradation of the base material following the design procedures prepared by USSCS and Sherard recommendations. It was found that the filter material taken from the dam and analyzed for grain size distribution doesn’t satisfy most of the filter criteria. On the other hand the treated sample of this same filter material showed better in satisfying most of the filter criterion and also the stocked filter material was contaminated due to improper placement and poor prevention. The analysis result (especially USSCS method) indicated that the treated (washed) filter material almost satisfies the geometrical criteria and it had a little bit fine (1.7-2.2 %.), which was still in the limit of the filter band. On the other side, the constructed sample was not satisfied the gradation curve. Because it was over fined, that 5.5-5.8% passes the fine limit of filter which can result clogging, poor permeability, weak draining capacity and crack for coming serviceability. Additionally the material contamination result shows, mostly on the underneath of stoke especially from ground to 80 cm because the material was near to unexpected runoff entry. Therefore the field manager or site engineer should apply efficiency checking and giving remedial measure carried out not only at quarry site but also during construction. Additionally design of quality control and quality assurance should properly apply