Index and Mechanical Properties of Collapsible Soils (A Case Study on Ziway-Arsi Negele Highway Project)

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Date

2019-12

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Addis Ababa University

Abstract

Collapsible Soils, unlike many other types of problematic soils found in Ethiopia, did not get the necessary attention in researches conducted to this date. However, due to their particular engineering characteristics, they exhibit large settlement upon wetting posing threat to embankments and foundations built over them. Due to lack of researches on collapsible soils and the limited attention given in engineering design manuals of the country, many professionals in the construction industry fails to clearly understand their index and mechanical properties. This research had the aim of assessing the index and mechanical properties of collapsible soils found between Zeway and Arsi Negele towns by taking the ModjoHawassa Dual Carriageway Highway Project, Lot 3; Zeway-Arsi Negele as a case study. To this regard, a series of field and laboratory tests were conducted on representative collapsible soil samples collected from the above-mentioned study area. Field density test has been conducted to determine the in-situ densities of the sampling areas. Furthermore, laboratory tests like specific gravity, grading analysis, Atterberg limits, and moisture-density relationships have been carried out to determine their index as well as mechanical properties. In so doing, it was observed that the soils have very low in-situ densities, mainly consist of sands and silts and low plasticity. Moreover, in order to investigate the collapse nature of the soil samples, collapse potential test has been carried out using one dimensional Oedometer by remolding the samples to their in-situ as well as maximum dry densities so as to perceive the nature of collapsibility of the soils at their natural state and at their compacted state. Accordingly, it was found out that the soils have moderate collapse potential at their natural state and does not exhibit any kind of collapsibility at their compacted state.

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Keywords

Collapsible Soils, Collapse Index, Collapse Potential, Index Properties, Mechanical Properties

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