Abstract

Geotechnical and geophysical investigation involving electrical resistivity survey and laboratory test of soil samples were carried out at Alaba Layout, close to the Federal University of Technology, Akure temporary site. Sixteen vertical electrical soundings were conducted within the study area and laboratory tests conducted on soil samples obtained at three different locations in the area. Three major lithologic units were delineated from the electrical resistivity survey results comprising topsoil characterized by mudstone topsoil, plastic clay/weathered basement and the fresh bedrock. Resistivity values for the various units range from 12 to 210 Ωm, 18 to 381 Ωm and 8084 to 47009 Ωm respectively. Depth to the basement estimated for the sixteen sounding locations vary between 4.1 m to 25.2 m. The geotechnical tests carried out on the soil samples indicated that the soils comprising the overburden materials in the study area graded from plastic organic clayey to intermediate plastic clayey soils. These soils have strong affinity for water absorption and swelling which will increase the activity of the clay minerals in the overburden materials. In addition, the overburden materials exhibit strong shrinkage ability thereby posing serious compaction problems to any engineering works, such erection of buildings, road construction and other forms of civil engineering works.

Key words: Engineering geophysics, flood, Atterberg limits, linear shrinkage.