Authors: Morrison, T. and Esonanjor, E.E.
Abstract
A geotechnical soil investigation was performed to determine the subsoil conditions at the proposed site to provide parameters for the design of foundation for a proposed modern market in Port Harcourt. Both field study and laboratory analysis of samples were done. Field works included five (5) number boreholes drilled to 20.3m by the use of Shell and Auger manually operated rig, six (6) number 10Tm CPT tests conducted to refused depth ranging from 12.00 to 21.00m and SPT-N values determinations. Disturbed and undisturbed soil samples were collected for
analysis. The disturbed samples were analyzed according to BS standard for index properties such as grain size analysis, Atterberg limits, moisture content, and bulk density, while relatively undisturbed samples were analyzed for strength properties and parameters. From the results, the subsoil in the area consists of a thick layer of lateritic clayey/sandy clay with a plasticity index of 40%, coefficient of volume compressibility (mv) 0.278m2/KN and cohesion 40KN/m2 at the top followed by a larger of 9.75m thick medium dense five to coarse sand with frictional angle 28 to 3500. Safe bearing capacities were computed for pad footings and raft foundation in the range of 122 to 173kPa and 122 to 151kPa respectively at various foundation width and LB rations. Groundwater was encountered between 5.64m and 6.10m below ground level.