Impact Factor (2025): 6.9
DOI Prefix: 10.47001/IRJIET
Impact Factor (2025): 6.9
DOI Prefix: 10.47001/IRJIET
The aim of this
research work is to evaluate the velocities distribution and lithological
changes within the subsurface, necessary for site characterization at a
construction site located in the oil rich Niger Delta of Southern Nigeria using
downhole seismic method. The downhole seismic survey was carried out with an
offset distance of 3 m, at an interval of 1 m to a depth of 30 m. The seismic
velocities which ranges from 457 m/s to 1972 m/s for the p wave velocity, and
291 m/s to 1066 m/s for s wave velocity connotes that there are two layers of
unconsolidated and consolidated sand in
the region under investigation. The range of Poisson’s ratio 0.16 to 0.23
determined for the unconsolidated sand layer and 0.24 to 0.29 for the consolidated
sand layer, gave a clear confirmation that the region under investigation is
made up of two lithological unit of sand, from the surface down to a depth of
14 m, and from 15 m to 30 m. The determined shear, bulk and Young’s modulus
were able to delineate the unconsolidated and consolidated sand layers by
registering low values down to a depth of 14 m. It is imperative to conclude
that the area under investigation is characterized with two lithological units,
the saturated and unsaturated sand layer of different elastic parameters. It
was also recommended that proper engineering remediation is required to improve
the strength of material down to a depth of 14 m, before erecting any
structure.
Country : Nigeria
IRJIET, Volume 2, Issue 9, November 2018 pp. 1-6
