Causes and Mitigation Measures for Slope Instability Problems of Belta–Otolo Road Project Gamo Gofa Zone, South Ethiopia.

Abstract

The project presents the investigation, causes and design of proposed mitigation measures for one cut slope related instability (land slide) locations stationed at Sta.68+020(ahead) to Sta.68+140(back) (RHS) part of Arbaminch-Kamba-Sawula Road project of LOT II: Belta – Otolo Asphalt Road Project located in Gamo Gofa zone,Southern part of Ethiopia. In this project work, first slide characterization of the cut slope instability areas which includes the land slide location, dimensional variables and engineering classification the land slide soil through detailed site investigation and testing was carried out. Finally, using the results of the investigation and combination of control and restraint mitigation measures were proposed and designed at the respective land slide locations so that the construction of road at these locations were finalized. Generally, it was observed that the provision of steep cut slope angles, the presence of relict residual bedding profiles and migration of moisture from prolonged rainfall duration were the main reasons for the instability of the cut slopes under this study.