Geotechnical Characterization of Geological formation at slump sites within South-western outskirts of Zunferu, North central ,Nigeria

Abstract

Slumping is destroying farmlands in the south-western outskirts of Zungeru. Sieve and Atterberg limits were conducted on samples of geological formation from the slump and stable sites to ascertain the geotechnical attributes that make the area susceptible to slumping. Surface geological reconnaissance reveals that the area is underlain by schist, amphibolite and granite. The schist unconformable underlain Doko member of Bida formation. which is the lithostratigraphic unit undergoing slumping. Coefficient of Uniformity ranges from 0.57 to 3.48 at the slump sites. This indicates that the slump sites formationis poorly graded formation.at stable site is 5. which indicates fair size grading. Natural moisture content is 1.9% at the stable site.. The value trrippled (2.2 to 6.6%) at the slump sites. Atterberg limit is similar in all the sites. their liquid limit is less than 40%. Their plastic limit and plastic index iare less than 20% and 7% respectively. The low atterberg limit value indicates that the shrinkage and swelling is not responsible for observed slumping. Poor formation particle size grading and high NMC caused slumping in the area. Retaining walls with drain pipes and vegetation will arrest observed slumping