Structural mitigation for stabilizing rock slope failure at Peradeniya on Colombo- Kandy Main Road: geotechnical and constructional aspects

Abstract

Rock slope failure at Kandy -Colombo highway near Peradeniya town has been identified as a major threat to the highway as well as the people and properties of the vicinity. This study proposes a permanent mitigation plan for the rock slope failures at this site. Study was initiated with the analysis of similar case studies and field studies on the site area and mitigation options. Two level surveys were carried out to collect topographical data for preparation of a 3D model of the slope. Material identification was done by using particle size analysis and plasticity tests; direct shear tests were carried out to determine the friction angle, cohesion and density of the material. Mitigation plan was designed according to the site conditions. The design was analysed for nine sections on the slope for its stability with the test results by using Geo-studio 2004 software. Reinforcements were proposed to improve the stability whenever needed. An appropriate drainage system was also designed having analysed the past rain fall data of the area. The proposed mitigation plan in this study is a highly stable, safe, trouble-free and economically feasible one, and that can be implemented on this site.