ASSESSMENT OF RIVER NIGER BANK STRENGTH FOR ONSHORE STRUCTURAL FOUNDATION WORK

Abstract

River bank erosion is an acute natural hazard all over the world. The same hazard is also frequent in River Niger. It is a generally known truth that the geotechnical features of any foundation construction have a significant impact on its state. This research evaluated the soil subsurface conditions of the River Niger Bank by evaluating the soil strengths and recommending appropriate foundation types for onshore structural foundation works. The deep soil investigations were conducted at the Jamata axis along River Niger. Soil samples were collected at depths ranging from 2.00 to 10.00 meters in four locations 2,500 metres apart to cover the stretch of 10 km at the river bank area of Jamata. Preliminary and engineering tests were performed on the soil samples. The results of preliminary tests revealed that dense sand materials were encountered and were found to be dominance in all four drilled locations at a depth between 6.00 – 10.00m. The laboratory tests showed that the amount percentage of fine sand ranged from 31.70 – 82.50%, natural moisture content from 7.50 – 22.00%, liquid limit ranged of 25.1 – 52.2%, plastic limit ranged from 18.7 – 32,40%, plasticity index ranges from 5.20 to 25.10%, Maximum Dry Density (MDD) ranged from 1387.95 – 1965.42 kg /cm3, specific gravity ranged from 2.20 – 2.80, California Bearing Ratio (CBR) between 2.96 – 9.81%, and the triaxial shear test ranged from 80.08 – 167.93 kN/m2. The outcome of the research concluded that the AASHTO classification of the examined subsoils conditions namely A-2-6, A-7, and A-2-7, and in addition to low in both the MDD and percentage CBR, will make the soils unsuitable for onshore structural foundation constructions and hence, there is need for stabilization before and structural foundation work. The outcome of this research will aid Engineers, contractors, designers and construction workers in the appropriate foundation type to be adopted for an onshore structural foundation at the Jamata axis of the River Niger bank.