Civil Engineering
Permanent URI for this collectionhttps://etd.hu.edu.et/handle/123456789/675
Browse
2 results
Search Results
Item CORRELATION BETWEEN INDEX PROPERTIES WITH SHEAR STRENGTH PARAMETERS FOR HAWASSA SOIL(Hawassa University, 2017-04-23) BATAMO BELIHUShear strength parameters (angle of internal friction and cohesion) are the key engineering properties of soil. In every situation finding these parameters by laboratory testing or by using advanced equipment may be uneconomical for clients during the preliminary design phase. So it is a common practice in geotechnical engineering to estimate these parameters by employing empirical equations from easily found engineering properties of soil. Correlations and empirical equations developed are site specific, and a good result will be found using them for soils from which they are developed. In this study an attempt was made to correlate shear strength parameters (angle of internal friction and cohesion) for Hawassa city soil from index properties. Detailed analysis was carried out by randomly taking thirty four samples from seven sub cities of Hawassa city. The sampling pits were dug manually using hand tools with plan area of 1.50 m by 1.50 m at depth of 3.0 m from the ground surface. From laboratory test results, most samples were found to be with very low values of density and no plasticity. The soil was classified as cohesionless soil of fine to medium sized sand with group name silty sand, sandy silt, silty, clayey sand, silty, clayey sand with gravel and well graded sand with gravel consecutively. Due to the nature of the soil, cohesion was exempted from correlation. The Influence of easily found index properties of soil on its shear strength parameter was studied, and a regression carried out for the selection of most influencing variables. This parameters identified as the grain size distribution, density, and water content of the soilItem CHARACTERIZATION OF COHESIVE SUBGRADE SOIL FOR FLEXIBLE PAVEMENT DESIGN (IN CASE OF WEZEKA-KONSO ROAD)(Hawassa University, 2019-10-22) MULUGETA REGASSA YIMAMRoad transport has a vital contribution for a nation development. Road has to be designed in a way that it can function in all season of the year, this could be achieved if the road is paved and the structural elements of the pavement is well designed. In general pavements are classified as rigid and flexible pavements. In rigid pavement loads are carried by the concrete itself thus the design requirement is the flexural strength of the concrete whereas in flexible pavement, the intention of the design is to reduce the deformation of the subgrade under a certain loading condition. Thus, flexible Pavement design needs proper material characterization so that failures in structural as well as functional could be mitigated. The aim of this study is characterization of cohesive subgrade soil for flexible pavement design in case of Wezeka – Konso road, Ethiopia. Identification of the Physical properties and classification of the soil was done according to AASHTO criteria. Resilient modulus was predicted from unconfined compressive strength. Additionally, a method has been developed for prediction of resilient modulus from unconfined compressive strength and index properties of soil. For both prediction models Microsoft excel was used to conduct the statistical analysis. The soils used for this study were low to medium plastic fine-grained soils. According to AASHTO soil classification system the soils were group in A-4, A-5, A-6 and A-7-5 categories. Statistical analysis shows that the relation between resilient modulus and unconfined strength was linear correlation. For this correlation the coefficient of determination value of R2 = 0.83 was obtained. For the second model which is prediction of resilient modulus from unconfined compressive strength and index properties the correlation was multilinear with coefficient of determination R 2=0.87. Due to the inclusion of index properties in the second model a better correlation was observed.