Geotechnical characterization of Soil susceptibility to Gully Erosion, Capitol, University of Benin, Benin City, Edo State, Nigeria

Abstract

A geotechnical evaluation and assessment of soil susceptibility to
erosion were carried out in Capitol gully, University of Benin,
Nigeria. Soil samples were collected with a hand auger from
three (3) sampling points in the study area at a depth of 1m. The
geotechnical properties of the soil samples analyzed in the Civil
Engineering Laboratory, University of Benin were Sieve analysis,
Atterberg limits, Compaction, Moisture content, and Shear
strength according to BS 1377: part 1-9, 1990. Results of Sieve
analysis indicates that percent passing 75mm sieve across
sampling points 1,2 and 3 ranged from 9.4% -55% . The liquid
limit values are 0.00%, 42.42% and 33.27%, while the plasticity
index values are 0.00%, 25.44% and 19.98% for sampling points
1, 2 and 3 respectively. The value of specific gravity ranged from
2.59 to 2.34, maximum dry density (MDD) values ranged 1.64 -
1.75 mg/m3
, and optimum moisture content (OMC) ranged
11.20% - 16.5% for sampling points 1.2.and 3 respectively. The
result of the shear strength characteristics across the three (3)
sampling points showed that cohesion C, ranged from 8.0kN/m2
-
20.93kN/m2
and angle of internal angle of friction, (Ф) ranged
from 13° - 23.81° respectively. The study confirmed that most
soils at the sampling locations were non cohesive comprising
mainly of loose sands with minimal amount of silt/clay present;
indicating that the physical characteristics of the soils is likely
responsible for its vulnerability to erosion and a contributing
factor to the formation of Gullies in the Capitol, University of
Benin, Nigeria. The poorly laterized soils observed in the study
area could also be attributed low specific gravity in the area.