Umudike Journal of Engineering and Technology

Standard penetration test (SPT) results obtained from the six geo-political zones of Nigeria were used to correlate soil properties and evaluate foundation bearing capacity and settlement characteristics using some conventional empirical/analytical models and numerical modelling. The SPT N-values were corrected to the standard average energy of 60 % (N₆₀) before the soil properties were evaluated. Prediction of soil properties was carried out for 100 kN/m² applied foundation pressure at nine footing embedment depths (i.e., 0.6, 2.1, 3.6, 5.1, 6.6, 8.1, 9.6, 11.1 and 12.6 m). Numerical analysis using Plaxis 3D, a finite element code, showed that the analytical/empirical methods for estimating allowable bearing pressure and settlement of shallow foundations gave acceptable results. Also, the results obtained show that the susceptibility of soils in Nigeria to compression is highest in the South - South (SS) geo-political zone and decreased in the order South - West (SW), South - East (SE), North - East (NE), North - West (NW) and North - Central (NC).  Average bearing capacity values in the ranges 150 – 350, 130 – 260, 135 – 310, 135 – 260, 100 – 200 and 120 – 230 kN/m² , were determined at embedment depths in the range 0.6 - 3.6 m for NC, NE, NW, SE, SS and SW geopolitical zones, respectively.  The bearing capacity values can be used as first approximation of foundation bearing capacity but do not preclude the use of site specific data.