Steep Slope Stabilization Under Seeping Water

Abstract

Construction of structures on a land created between the upper and the lower plateau of a hill slope has always been a challenging task for geotechnical engineers. Creating adequate space under such conditions involves huge earthwork in cutting and filling, resulting in unstable steeper slopes in several locations. The problem gets further aggravated with the presence of high water table pressure and seeping water through the slope. This paper refers to a case study of constructing refinery unit road used for the movement of product-laden trucks across a slopy terrain where a maximum rainfall of 4000 mm is recorded annually. Due to the space constraint at the site, construction of stable slope with gentle inclination was not feasible. Hence, the steeper slope of 80–85° inclination was constructed with reinforced earth (RE) wall on filling side (650-m length) and 65–70° slope of 350-m length was constructed using soil nailing with gabion toe wall in the cutting side. This paper discusses in detail construction methodology carried out at the site along with various challenges faced during execution of soil nailing slope including details of nails, load test results, gabion toe wall details, reasons of local slope failure and rectification measures adopted.