In-situ foundation characterization and design in Ese Odo Local Government Area of Ondo State, Southwestern Nigeria

This study aims at assessing and characterizing the subsoil types/profile to determine the engineering characteristics of the underlying soils and provide appropriate foundation design alternatives, in Ese Odo area of Ondo State, Nigeria using geophysical and geotechnical methods. The geophysical method involved six vertical electrical soundings (VES) and complemented by two cone penetrometer tests and eight trial pits/boring where representative soil samples were obtained and analyzed in the laboratory, in accordance with relevant geotechnical engineering standards. The VES shows a predominant HK and KHK curve types which account for 33.3 % each. The upper 5 m is characterized by moderate thickness (3.3 – 9.6 m) which could dissipate the influence of structural load effectively and high resistivity values (380 – 2439 ohm-m) to sustain the structural load. The average bearing capacity of 100 KN/m2 is recommended for design of bases/footings for shallow foundation at a depth not less than 2.8 m in the area with the total settlement less than 50 mm tolerable limit, for foundation width ranging from 0.5 to 3.0 m. The recommended range of allowable bearing capacity for strip foundation is 221 - 459 KN/m2, while square is 352 - 641 KN/m2. For driven pile at 5 m, 10 m, and 15 m, the adopted allowable capacity varies between 66 – 118 KN, 212 – 357 KN, and 440 – 717 KN respectively. The allowable bearing capacity for bored pile ranges from 35 – 71 KN, 88 – 170 KN, and 159 – 297 at depth levels of 5 m, 10 m, and 15 m respectively.