Slope stability analyses of the proposed reconstituted slope of the quarry heights drive landslide, Durban, South Africa

Abstract

Urban sprawl into the more hazardous steeper terrain surrounding the Durban area hasincreased the risk of landslides in these areas. The Quarry Heights Drive landslide in Durban occurred in November 2011 in a low-cost housing settlement which led to damages amounting to millions of US dollars and the loss of a life. The geology at the site consists of sandstones of the Vryheid Formation intruded by a dolerite sill which was subsequently displaced by a reverse-dextral fault. The entire sequence is capped by clayey weathered residual and transported material. A reconstituted slope has been proposed for the site which involvesre-profiling of the slope and replacement of the failed materials with free draining engineering fill to act as a mass gravity berm to support the slope. Geotechnical characterization of the materials constituting the proposed fill as well as the in situ materials has been undertaken. The stability of the proposed reconstituted slope has been assessed under two critical groundwater conditions using the Morgenstern and Price method in Rocscience Slide v.6. Results obtained from the analyses indicate stability of the proposed reconstituted slope. .