Assessment of Subsurface Competency Using Geotechnical Method of a Proposed Structure F.C.T Nigeria

Abstract

Structural failure has been recently happenings mostly in the commercially populated states along the coastal line in Nigeria. As a result, an open field at a chosen location in Abuja, Nigeria, was investigated. For the purpose of this study, test bores were drilled and Standard Penetration Tests (SPT) were conducted at every 1.5 m interval up to a maximum depth of 12.0 m with the bearing pressure ranging between 20 kN/m2 and 1000 kN/m2 . 3 test bores’ were drilled within the plot location, and samples were obtained at the test bores locations for laboratory analysis. Findings revealed that subsurface lithology found at the site within the explored depths of 0.0 ~ 12.0 m is mostly silty sand, laterite, sandy clay, silty clay, clayey sand, and weathered rock. The findings from the sub-soils of the different places and their bearing pressures were computed with SPT N value. Building foun dations may be rigid raft foundations at a depth of 2.0 meters below the present ground level, according to bearing capacity values that range from 20 kN/m2 to 60 kN/m2 at 1.5 to 3.0 meters. The recommended building foundations take into account the sub-soil’s characteristics at the drilling places at a depth of between 1.0 and 3.0 meters. The structure might also be supported by frictional piles buried 10 meters beneath the surface.