Rockfall and Subsidence on Mumbai - Pune Expressway

Abstract

Mumbai - Pune, India’s first Expressway which crosses the mountainous and rugged Deccan Trap province, suffered from major rockfall and landslides in 2003 and 2004. A significant number of accidents and casualties have been reported due to occurrences of such events. On the basis of frequency and magnitude of the recorded incidences of rockfall, seventeen critical areas have been identified for investigations and mitigation. One of the problematic areas which suffered from rockfall and subsidence at km 41 on the expressway, adjacent to a tunnel (Adoshi), has been chosen for detailed study. This area extends for 500 m along the expressway and the embankment has subsided by 2 to 3 m along the entire length. Based on the geological, geomorphologic and geotechnical investigations, causative factors for rockfall and subsidence at this location have been established. This paper presents the field investigations, probable causes, stability analysis and remedial measures to control the subsidence and rock fall.