Soil Bearing Parameters and Settlement Prediction Using CPT Data in Southwestern Nigeria

Abstract

The study was aimed at deriving important soil parameters relevant to civil engineering construction in schistose quartzite/quartzite dominated soil of RUGIPO, Ondo State, Nigeria, using cone penetration test (CPT). Key engineering parameters’ findings revealed a high degree of overlapping values within the two geological formations. However, both soils are very dense, stiff/hard soil, with a high dominance of coarse particles (sand) over the finer soil matrix (silt). Soil from quartzite has better bearing pressure (avg. 405 kN m^-2) than schistose quartzite (324 kN m^-2), even above the regional average of 346 kN m^-2. The CPT material index with a regional average of 2.40, with schistose quartzite and quartzite showing average values of 2.39 and 2.42, and average soil permeability of 6.19×10^-7 m s^-1 and 4.498×10^-7 m s^-1, respectively. The soils have a mean CBR value of 38%, with the CBR of schistose quartzite (35%) less than that of quartzite (42%). The regression models between all the parameters correlated gave positive correlation coefficients, especially CBR and  (0.6522), R_D and CBR (0.6536), S_u and q_c (0.9849). The practical implications of the result indicated that both soils are competent for construction (pavement, foundation, and embankment construction) in both geological formations.