ISSN 2319-5347, ISI Impact Factor: 0.763

VOLUME 05 NO. 04 OCTOBER 2016:

Title:      Assessment of Sub-Soil Geotechnical Properties for Foundation Design in Part of Reclaimed Lekki Pennisula, Lagos, Nigeria
Authors:   Faseki, Oluyemi Emmanuel, Olatinpo, Olusegun Ayobami, Oladimeji, Akinsile Richard
Abstract: Assessment of engineering geologic condition was undertaken in Phase I housing estate in Lekki Pennisula, Lagos, Nigeria with a view to delineating the stratigraphy and estimating the engineering properties of shallow formations for construction purposes particularly in foundation applications. Field techniques such as borings, Standard Penetration Test and Cone Penetration Test were deployed. 2 boreholes were drilled each to termination depth of 30.0m. Samples of strata encountered were subjected to laboratory analysis such as natural moisture content, grain size testing and Atterberrg limits tests. The results showed that the subsurface is underlain essentially by loose to medium dense silty sand (0.0 – 3.0m) with average SPT-N value of 11, friction angle of 320 , natural water content of 17.0 – 22.0% overlying a soft silty clay (3.0 – 4.50m) with low cohesion value of 24.0KN/m2 , SPT-N of 4, qc value of 23, unit weight of 15.50KN/m3 and high natural water content of 88 – 92% cum void ratio of 1.14. Beneath these layers is very loose clayed sand (4.50 – 9.0m) having low qc of 18, SPT-N of 5, angle of internal friction of 300 . These layers are further underlain by medium – dense sand (9.0 – 30.0m) having (20 – 32) SPT-N values, (0.40 – 0.45) void ratios, (19.50 – 20.50KN/m2) unit weight and (32 – 330) angle of internal friction which are typical of appreciable foundation material. The poor engineering properties of the soil within the shallow foundation zones preclude the adoption of shallow foundation for the proposed structure. Pile foundation installed to at least at 12.0m within the mechanically stable medium – dense sandy strata is recommended for the proposed structure.

Keywords: Geotechnical Properties, Pile Safe Working Load, Standard and Cone Penetration Test, Boring, Lekki Pennisula, Lagos Nigeria
Pages:        120-128

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