Subsurface Soil Characterization of a Site for Infrastructural Development Purposes in D/Line, Port Harcourt, Nigeria
H.O Nwankwoala, T. Warmate

The study aims at characterizing the sub-soil types and profile to ascertain the geotechnical properties of the underlying soils in a site in D/Line, Port Harcourt, Nigeria for appropriate foundation design considerations for infrastructural development purposes in the area. Borings were accomplished using a percussion rig with the aid of augers. Representative samples were analyzed in the laboratory in accordance with relevant geotechnical engineering standards. The study revealed that the surface is underlain by a soft – firm sandy clay (about 6m ) of moderate-high compressibility with undrained Strength of 46KN/m2 overlying a firm-stiff sandy layer. Beneath these layers, are loose sandy layers (with an angle of friction, of 29o) overlying a medium dense sandy layer (with an angle of friction of 31o). Underlying these layers is a dense sandy layer (with an angle of friction of 36o). The allowable bearing capacity profile of the sub-surface shows low bearing capacities characteristics (1m - 2m: <110KN/m2). These values are relatively lower than the projected foundation loading. Pile driven to at least 5m into the sand layer is recommended as the foundation option for consideration for civil engineering structures in the study area.

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