Engineering Soil Characterization in Sululta Town, Central Ethiopa
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Date
2017-06
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Addis Ababa Universty
Abstract
Soil characteristic is a measure of soil's suitability to provide a proposed civil structure. Soil characterization is essential to provide the information for design and construction of engineered structures. In a country like Ethiopia which is developing at high growth rate and which needs many construction works in the future, geotechnical investigation on the engineering characteristics of soil is very essential. Sululta Town one of the towns of Oromia special zone surrounding Finfinnee in which big volume of construction is being undergoing. Thus, this research is concerned with engineering soil characterization in Sululta Town. The study was conducted in order to characterize soil of the study area for engineering practices. Specifically, the study focuses on index properties and strength and consolidation tests in order to examine the soils’ characteristics. In order to characterize the soils, laboratory tests index properties such as Natural moisture content, Grain size analysis, Atterberg limits test, Specific gravity and Free swell conducted on disturbed samples and engineering properties such as shear strength and consolidation tests were conducted on undisturbed samples. The soil of the study area was classified by using Unified Soil Classification System (USCS) and American Association of state High way and Transportation Officials (AASHTO) classification schemes. The soil type was identified as it is uniform throughout the town. Grain size Analysis result showed that, the area characterized by fine grained (cohesive) soils. Laboratory test result revealed that Natural moisture content of the soil ranges from 23.27 to 65.48. The Liquid Limit ranges from 41.8 to 91.5%. Likewise, the plasticity index in percent of the soils ranges from 11.63 to 44.59%. Besides, the free swell test results showed range from 30% (low expansion potential) to 80 % (high expansion potential). As a result of the index property tests the soil of the study area has been classified as A-7-5 as per AASHTO classification system whereas soils classified as ML and MH by USCS. Based on the shear strength and consolidation laboratory tests, bearing capacity and settlement analysis for the soils was also conducted. The main geotechnical problems that affect design and development of civil structures in the town were identified as existence of shallow Ground Water table, cohesive soils of high plasticity characteristics and low bearing capacity of the soils. Bearing capacity analysis result showed that, the soil of the study area characterized as low bearing capacity soils that needs improvement before construction of large structures. Finally, the conclusion drawn from the present study showed that the soils of the study area are not suitable for engineering practices unless it improved by appropriate measures.
Key words: Allowable Bearing Capacity, Liquid Limit, Soil characterization, Soil Classification, Sululta town
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Keywords
Allowable Bearing Capacity, Liquid Limit, Soil characterization, Soil Classification, Sululta town