Assessment of the strength of foundation materials in some parts of Afikpo, Nigeria, using siesmic refraction

Abstract

Seismic refraction field method was carried out in five communities in Afikpo located between latitudes 5o521N and 5o571N and longitudes 7o521E and 7o581E using a 3 channel digital type signal enhancement seismograph to determine the strength of foundation materials. Results from the 10 sites investigated show that seismic waves from the hammer source penetrated only the first three layers of the earth. Average thickness of 3.6m (probably sandy clay) and 11.8m (probably gravelly sand) was obtained for the first and second layers respectively. The first and second layers have average Poisson ratio (n) of 0.16 and 0.28, average shear modulus (m) of 3.54 x 108 and 33.74 x 108N/m2, average bulk modulus (k) of 0.72 x 109 and 15.04 x 109N/m2, average young modulus (E) of 0.82 x 109 and 9.54 x 109N/m2 and average lames constant (l) of 2.52 x 109 and 29.26 x 109N/m2 respectively. These results show that soils in the area are thick, rigid and well consolidated. The soils can withstand stress and as such are suitable for engineering construction work..

Keywords: Afikpo, foundation materials, modulus, refraction and strength

Nigerian Journal of Physics Vol. 18 (1) 2006: pp. 33-38