Analysis of Slope Instability along an International Road in North Africa

Abstract

Number of observed landslides incidences is documented along an international road in North Africa (Algeria). The instability incidences had to be dealt with during the development along the road by doubling the direction of traffic. The presence of the clays and/or colluviums deposits over marls base layer is the main explanation for the failure. At the described sliding area, the slip surface starts from the vertical crack at the edge of the road and extends down to the interface between the Clay and the Marl. The slip surface follows the Clay-Marl interface down to the toe of the slope. The geometry of the slip surface at the sites is confirmed based on boreholes drilling and dynamic penetration resistance profiles. Stability analysis of the slide is carried out using the residual drained strength along Clay-Marl interface. Intact to fully soften drained strength is used on the slip surface at locations other than the clay-Marl interface. The aim of this paper is to document; a) one of the observed landslides areas along the road, b) the investigation carried out to characterize the ground conditions as well as the geometry of the instability surfaces, c) the analysis carried out to determine the possible causes of the instability, and d) the potential solutions to stabilize the landslides area.