Shallow Site Investigation using Seismic Refraction Method: Case Study of FUPRE Stadium and Its Environs

Abstract

The shallow site investigation was done in the second campus of Federal University
of Petroleum Resources Effurun (FUPRE) stadium and its environs with the aim
to determine the shallow site level and also to estimate some geotechnical
parameters for potential construction sites within the study area with the
application of seismic refraction method. The research was done using
seismograph (PASI GEA 24 model) using 24 geophones with 4 m spacing and the
traverse distance for the area of investigation is 100m. The data acquired was
interpreted after the unwanted signal has been removed in order to identify and
estimate the thickness layer and velocities of different subsurface interfaces. From
the three traverses employed around the investigated area, the results showed that
the subsurface of the study area is made up of three layers. The first layer is a top
soil with an average thickness of 7m and the P-wave velocity is 284.5 m/s. The
second layer, which is a weathered Phyllite composition, has an average thickness
and P-wave velocity of 24.5 m and 419.2 m/s respectively and this indicates that
the saturated zone in this layer is vertically extensive. The third layer has the pwave
velocity of 765.6 m/s, however, all the three layers has the same Poisson’s
ratio value of 0.35 and density value of 1800 kg/m3. From the values of other
geotechnical parameters; which are young modulus, bulk modulus, shear modulus
and s-wave velocity. It is concluded that the first two layers are poor bearing
capacity that have low shear strength and high compressibility due to the low
values of the parameters compared to the third layer; however an additional
geophysical method is recommended for more revelation of geophysical
characteristics or features.