SLOPE STABILITY ANALYSIS USING COMPUTER SOFTWARE FOR BLACK COTTON SOIL OF NORTH – EASTERN NIGERIA

Ashiru M. Ashiru, Jacob E. Sanni and Sule Mohammed

Department of Civil Engineering Technology,

The Federal Polytechnic, Nasarawa, Nasarawa state, Nigeria.

E-mail: ashiruashiru@yahoo.com

Abstract: Black cotton soils found across the globe have been described by researchers as problematic soils due to the present of montmorillonite and kaolinite minerals in large quantities. Its swell-shrink movement has been reported to pose serious problems to engineering structures and lives from landslides failures. This research work focuses on stability analysis of slope using limit equilibrium method as a technological solution to the adverse effect of these routine slope failures. The study utilises three limit equilibrium methods: stability charts, SLOPE/W software and traditional methods. There is no difference in the application of these analyses because they are all formulated based on the static of equilibrium and slices discretisation. The results obtained under dry condition from the entire methods shows that, the slope is safe; although, at wet situations, all methods indicated instability. Comparing the results between techniques shows that Bishop’s simplified method is similar with Morgenstern Price’s method. Furthermore, the results from Janbu and Ordinary method in some situations are similar. It has been demonstrated that loads, pressures and shear strength parameters significantly influenced the factor of safety for critical slip surfaces and the stability state of a slope.