An integration of electrical resistivity method and geotechnical analysis for foundation investigation: A case study of Talba Estate, Minna, Niger State

Abstract

An integration of electrical resistivity and geotechnical analysis were deployed in studying the subsurface geology of Talba estate along Minna-Bida road. Electrical resistivity profiling and sounding (HRP and VES) were conducted from AB/2 of 1m using the ABEM Terramater SAS 300C. Schulumberger array was deployed for the vertical electrical sounding. Soil samples were obtained from trial pits dug to 1.5m deep. The results indicated an area comprising basically of granitic rocks covered in some places bt top soil. Electrical resistivity revealed a two layer case comprising of the top soil and bedrock. The top soil has a mean resistivity of 102ꭥm at average depth of 2.1m. The bedrock (granite) has a mean resistivity of 341.1ꭥm. The Atterberge limit test indicates inorganic clay of low to medium plasticity. The California Bearing Ratio shows a moderate bearing capacity. The maximum dry density ranges from 1.80 to 1.98% and optimum moisture content ranges from 8.0 to 14.0%. The sieve analysis indicates a well graded gravel. The soil samples analyzed shows relatively good geotechnical characteristics. Shallow foundation is recommended for the Talba Estate and the foundation should be placed firmly on the bed rock for firm support. This will require striping of the top soil of about 2.1m average thickness.