Geotechnical Investigation of Road Failure Along Ogheghe, South-South, Nigeria

To assess the geotechnical properties of the soil, three different soil samples were collected from both failed and unfailed sections of Ogheghe Road in South-South Nigeria. These samples were analysed for particle size distribution, liquid limit, plastic limit, maximum dry density (MDD), optimum moisture content (OMC), and California Bearing Ratio (CBR). The results showed that for Sample One, the OMC and MDD were 35.88% and 1.42 g/cm³, respectively, with plastic and liquid limits ranging from 20.88 to 20.92% and 39.42 to 49.62%. The CBR values ranged from 15.20% to 24.00% in unsoaked conditions and 11.61 to 17.53% in soaked conditions. For Sample Two, the OMC and MDD were 13.15% and 1.72 g/cm³, respectively, with plastic and liquid limits ranging from 18.91 to 20.38% and 31.25 to 40.35%. The CBR values ranged from 12.00 to 19.71% in unsoaked conditions and 10.63% to 11.75% in soaked conditions. For Sample Three, the OMC and MDD were 19.24% and 1.40 g/cm³, respectively, with plastic and liquid limits ranging from 17.95 to 18.15% and 31.22 to 40.73%. The CBR values ranged from 6.09 to 7.65% in unsoaked conditions and from 4.63 to 7.29% in soaked conditions. These results were compared to the specifications established by the Federal Government of Nigeria for roads and bridges (1997); overall, the result revealed noticeable deviations from standards. This implies that the soil along the Ogheghe road is unsuitable for use as subbase and base materials and is a significant contributing factor to the road's failure.