The Use of Seismic Refraction and Geotechnical Parameters to Conduct Site Investigation – A Case Study

Due to the disastrous effects of building collapse in recent years as a result of improper site investigation, the site for a multi-purpose storey building at New Atuabo in Tarkwa, Ghana was investigated using seismic refraction and some geotechnical parameters. The results for the seismic refraction revealed that there are four strata. The site has a top soil of 1.5 m thickness and second layer made of 8 m thick weathered material. The third and fourth layers being saturated material and bedrock respectively have vertically extensive depths. The seismic refraction also showed an average depth to water table of 9.5 m. The geotechnical tests conducted were Dynamic Cone Penetration Test (DCPT), Sieve Analysis and Atterberg's Limit Test. DCPT was conducted to estimate the bearing capacity of the soil. The safe bearing capacity was 294 kN/m2 at a depth of 2.2 m. Sieve analysis results showed that the soil is well graded. And finally, Atterberg's Limit Test was conducted to know the plastic nature of the soil. This yielded an average plasticity index of 7.75 %, which means the soil is silty with low plasticity. The plasticity index was used to estimate the swelling potential of the soil and was found to have a low swelling potential.