Geophysical and Geotechnical Investigations of a Landslide in Kekem Area, Western Cameroon

Pouyon Dieudonné Epada, Ganno Sylvestre, Tabod Charles Tabod

University of Yaoundé I.
University of Yaounde I, National Civil Engineering Laboratory.

DOI: 10.4236/ijg.2012.34079                

Abstract

Geophysical and geotechnical surveys were conducted in the Western Cameroon (Kekem area) following a landslide on argillaceous material in order to understand the triggering processes and mechanisms of this landslide and to assess the stability of the slope. The geophysical soundings consisting of vertical electrical soundings with the Schlumberger electrode array configuration were carried out to monitor the behaviour of electrical resistivity in the landslide. Geoelectrical data showed a zone of low resistivity values identified as a clayey sand-filled aquifer. This aquifer played an important role in the triggering process of the landslide. Geotechnical soundings showed that the aquifer had a thickness of 7.0 m. The depth from the landslide crest level to the failure surface reached 3.0 m and 20.6 m. Laboratory tests were then carried out in order to evaluate the cohesion of the soil and the angle of internal friction, and to calculate the safety factor in view of making a stability analysis. The laboratory results exhibited a soil with low consistency, almost doughy. The mean value of the safety factor (1.4) been lower than the slope stability coefficient (1.5), revealed that the slope is unstable, likely to know at any moment a reactivation of the slide. This study showed that electrical soundings coupled with geotechnical surveys are useful tools for the characterization of landslides.

Keywords

Landslide; Resistivity; Argillaceous Material; Basal Undercutting; Kekem; Cameroon

Conflicts of Interest

The authors declare no conflicts of interest.

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