Journal of Engineering Geology Volume XLIV, Nos. 1 & 2 A bi-annual Journal of ISEG June & December 2019 Geological and geotechnical challenges faced during construction of Rohtang highway tunnel - A case study Pathak*, Mridupam Geologist, PEMS Engineering Consultants Pvt. Ltd., D2-ICT JV, Rohtang Highway Tunnel Project, Manali, Himachal Pradesh, India Saini, Sandeep Kumar Geotechnical Engineer, Intercontinental Consultants and Technocrats Pvt. Ltd., D2-ICT JV, Rohtang Highway Tunnel Project, Manali, Himachal Pradesh, India *E-mail of corresponding author:
[email protected]) Abstract Tunnel projects in complex geological setting like the Himalayas are very unique due to the geological uncertainties and challenges to tackle them. Detailed geological investigations are an absolute necessity for effective design and construction due to large variations in the tendered and encountered rock classes witnessed here. The Seri Nalla Fault zone was encountered unexpectedly prior to its expected location. DRESS methodology proved very effective in countering the Seri Nalla zone. To counter high deformations induced in the shotcrete and lattice girders due to the high in-situ stresses, Lining Stress Controllers (LSC) are very effective. This case study presents the geological challenges faced during construction of the Rohtang Tunnel and the subsequent efforts undertaken to tackle them. 1.0 Introduction: The 8875 m long, single tube, bi-directional, two lanes, Rohtang Highway Tunnel is presently being constructed across the Pir-Panjal ranges of the Himalayas near Manali, Dist. Kullu in Himachal Pradesh. When completed, this tunnel will provide all weather connectivity between Manali and Lahaul. The Rohtang Highway Tunnel is part of a wider project to provide an all weather road connection between Leh region and the rest of India, via the Manali-Sarchu-Leh road (NH 21).