Browsing by Author "Adane, Lemma"

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    Characterizing the Influence of Ballast Flying
    (Addis Ababa University, 2016-03) Adane, Lemma; Henok, Fikre (PhD)
    Ballast flying is understood as cause of track deterioration in many countries over where high train speed is operated. The deformation and degradation behavior of ballast under static and dynamic load cause the ballast to fly early from under the track. In this thesis, the railway ballast particle force equilibrium is analyzed through basic mechanics and mathematical formula and a discrete element model is set up to discover the factors and influences. Ballast flying is correlated with ballast shape and mass, especially the ballast shape mass ratio corresponding to operation speed. Ballast interlock ability governs the ballast flying possibility and severity. Ballast flying possibility increase with ballast bed acceleration. The performance of ballasted track depend not only on its design, but also the way and quality of maintenance ,ballast needed to analyze the shape and mass of ballast material used to reduce the flying of ballast under track. This thesis investigated the effect and influence of ballast flying using a Discrete Element Modeling (DEM) approach. Results show that ballast flying particle is correlated with ballast shape and mass, aggregate gradation and ballast interlock ability. From DEM output it can be conclude that finer and non-uniformly graded aggregate are easily fly under railway track during operation and ballast with high angular shape resulted in the highest shear resistance or high stability. Acyclic loading analysis was conducted for angular particles relatively low confining pressure for analysis of particle fragmentation the generated assembly of angular particles undergoing fragmentation at various load cycle. from the simulation observe that though the mechanical load increase the fragmentation of railway ballast increases and finally leads to ballast displacement which lead to ballast flying. As the applied normal force increased, the shear force also increased primarily influenced by the shape effects of aggregate angularity and surface texture. Yet, a rough surfaced rounded particle had shear strength higher than that of a smooth-surfaced angular particle. The fact that rounded gravel particles have less aggregate interlock compared to crushed angular aggregate to transfer shear force can be explained by the bilinear contact force paths for the rolling and climbing up of the rounded particles. Angularity and cubical particles have high resistance to the vertical displacement under traffic loading because the inter particle force high when compared with the spherical and rounded/circular particles.
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    Sustainability at Tibila Irrigation Based Integrated Development Project
    (Addis Ababa University, 2012-06) Adane, Lemma; Aberra, Yohannes (PhD)
    This study analyzed the sustainahility of Tibila irrigation based integrated development project loea/ed in Arsi Zone of Oromia region, Ethiopia. Results are based on primOly and seconc/Cl1y dala collected f rom a sample survey of 110 households, focus groups discussion and key informant interviews as Hlell as secondwJ' documenl analysis. Analysis in descriptive s/o/is/ieal methods using SPSS, IBM is used and analysis of qualitative information supplemented the result. The project was analyzed against socio-economic, technical and environmental sus!cdnability 's. The scheme is a new large scale irrigation based development project under implementation and development. lJ was planned to cover about 7000ha of land when totally completed and will support a population more than 16000. Currently about 2000/emuers are using 1200ha of land to produce with. The results Ii/ the sludy revealed Ihal 'within the fhree year lim e, the farmers were producing 3-6 rounds and il is fo und fhal farm households have started 10 grow crops which were not previously grown in the areas such as passion fruits. It was also found (hat il has a positive hnpact on their ;'1come, on employment improvement as well as on the living standard oftheirfamilies. In addition, through time beneficiclIY farm households depend more on the production ji-om their irrigated/ields, which enabled them to harvest more than once a year. Therefore, as beneficiOlY farmers shift to high value but perishable commodities, emphasis should be given to market ;'1g extension, espedal/y infadhtaling markels and markel linkages to farmers. Furthermore, Through time Ihe demand for irrigation waler increases among benejiciclIY farmers. As a result, scarcity of water especially during the peak period is experienced Some conflicts on waler use (mel distribution are also experienced among the benefiCiaries due 10 certain technical faulls, management challenges and some inefficiency's. Even though Environmental challenges such as sahnity, logging and erosion are al their inilial stage, emphasis should be given to water shed managemenl and improvedfarming land and in-;gation waler management practices. Waler User Association or organization and farmers have /0 be strengthened and empowered in depth in technical, i.e. water managemenl, fanning lechnologies, institutional and scheme adminiSlraiions and in environmental issues 10 use Ihe scheme on suslainable basis \l llile keeping the socia-economic and ecological balances in the basin. (Key words: - Sustainability, Water management, socio-economic and ecological balancel