Landslide sensitivity assessment of existing twin tunnels: A case study of National Highway-76 between Udaipur - Pindwara, Rajasthan, India

Highways motorway tunnel failure is a major problem in rocky mountainous regions. Modes of failures are in various ways includes failures of cut hills close proximity to the tunnel crown, along the longer axis, internal part of the tunnel and collapse of the civil construction structure. To ensure their continued safe operation as well as appropriate repair and improvement works, a wide range of investigations has been carried out to confirm the conditions of tunnels and establish the causes and extent of deterioration and damage. The geometry of the slope surface, material profile and their spatial distribution, material properties viz. geo-mechanical, structural, phreatic surface, and local climatic conditions are the primary causes. The earthquake force, distributed load and vehicle induced forces acting upon the tunnel area aggravates the failure. Tunnel stability status analysis and data interpretation from the tunnel area helps in predictive assessment of probable modes of failure. Looking to the frequency of failures in the cut hills of adjoining part of the tunnels and traffic blockade, a study has been carried out on twin tunnels of national highway number 76 between Udaipur-Pindwara, Rajasthan India. The twin tunnel road passage is part of the folded Aravalli mountain chain.