Gravity survey was carried out to determine the sub-surface spatial bulk density distribution for geotechnical investigation. The survey involves the determination of station coordinate (Lat, Long and height) and observed gravity. Gravity measurements were made in survey loops using LaCoste & Romberg gravity meter, starting off at known base station and ending at the same base station. Seven station locations were spread out across the survey area in order to get good range of vertically (rather than horizontally) spaced stations. Corrections were carried out to obtained bulk density that truly represents the subsurface geology across the area, such corrections are terrain, drift and tidal corrections. Two methods were investigated to determine the bulk density. The Nettleton’s and Parasnis’ methods, the bulk density values obtained from the methods were (2.6g/cc±0.2329) using the Nettleton’s method and (2.5919g/cc±0.9612) using Parasnis’ method respectively. The bulk density values obtained were inferred to be crystalline/consolidated sedimentary rocks which would be suitable for geotechnical construction purposes.
Keywords: Bulk Density, Tidal correction, Sedimentary, Gravity survey and Geotechnical.
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