Geoengineering Deterministic Properties of Tropical Red Soil in Sobe, Edo State, Nigeria in Relation to Civil Engineering Structure

Authors : Falowo Olumuyiwa OLUSOLA

Pages : 226-241

View : 11 | Download : 8

Publication Date : 2022-07-04

Article Type : Research Paper

Abstract :The long serviceability expectancy of civil engineering structures depends on the index properties and bearing capacity of the foundation soil. Therefore, the study of engineering behaviour of soil is extremely important during the design, construction and post construction phases of civil engineering projects. This study investigates the index properties of Sobe tropical red soil in relation to building foundation, embankment, and flexible pavement constructions. The study adopted geochemical analysis, in-situ cone penetration test, borehole logging, and geotechnical laboratory soil analysis using American Standard of Testing and Material. Findings revealed the USCS and AASHTO class of the soil to be CH – CL insert ignore into journalissuearticles values(medium graded soil); and A-7-6 respectively, signifying poor foundation material, of high compressibility and expansion, with intermediate - high plasticity. The soil is characterized by unit weight insert ignore into journalissuearticles values(av. 18.3 KN/m2);, soaked CBR insert ignore into journalissuearticles values(av. 7%);, cohesion insert ignore into journalissuearticles values(av. 26.4 KN/m2);, angle of friction insert ignore into journalissuearticles values(18°);, compression index insert ignore into journalissuearticles values(0.4489);, compression modulus insert ignore into journalissuearticles values(2.78 N/mm2);, coefficient of volume compressibility insert ignore into journalissuearticles values(0.7721 m2/KN);, group index number insert ignore into journalissuearticles values(11.6);, plasticity index insert ignore into journalissuearticles values(34.74 %);. The material showed average bearing pressure of 111 KN/m2 at 1 m depth for building foundation. The average insert ignore into journalissuearticles values(av.); values of the major mineral oxides present in the samples are Na2O insert ignore into journalissuearticles values(av. 1.98 %);, K2O insert ignore into journalissuearticles values(av. 2.54 %);, Al2O3 insert ignore into journalissuearticles values(av. 18.79 %);, Fe2O3 insert ignore into journalissuearticles values(av. 19.83 %);, and SiO2 insert ignore into journalissuearticles values(av. 61.18 %);. However, Al2O3, Fe2O3, and SiO2 constitute 95 % of the mineral oxides. The silica - sesquioxide ratio insert ignore into journalissuearticles values(Se); of the soil showed that all the soil sampled soil are lateritic with a range of 1.27 – 1.96 insert ignore into journalissuearticles values(av. 1.59);. The soil has fair to poor stability for embankment slope, thin cores, blankets and dike sections. Thus using the group index and CBR design chart for flexible pavement, the combined thickness of base and surfacing should be 30 cm and 38.1 cm for sub-base/subgrade course. In conclusion, the soil required improvement or stabilization either with chemical insert ignore into journalissuearticles values(lime, cement, fly ash or asphalt); or by mechanical method, which would invariably reduce its plasticity/compressibility, and increase the shear strength and bearing capacity.
Keywords : Geochemical, Compression modulus, Embankment, Flexible pavement, Footing

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