College of Engineering, Pune, India
Online published on 6 February, 2020.
Tunneling work carried out in mixed geology of Himalayan ranges in India has always been a difficult task due to its complex geological conditions and unpredictable nature of the encountered rock along the tunnel. So, in such geology construction of tunnel by conventional method can prove hazardous. In such cases, New Austrian Tunneling Method (N.A.T.M.) was introduced in tunneling, which proved beneficial in many ways from construction point of view.
N.A.T.M stated the use of reviewing the supports system based on the obtained rock conditions, which made it clear and easier to provide a suitable support in order to restrain the rock movements and prevent the failure of supports provided. For this purpose, certain rock mass classification system have evolved over a period of time based on the empirical data obtained and were used to derive the rock type.
This paper focuses mainly on the research work related to a case study of an ongoing tunnel on the Chandigarh-Manali highway (Kiratpur Ner chowk) in the Himalayan ranges wherein the classification of tunnel was done by RMR classification followed by theoretical approach including classification of rock by Q systems wherein the various parameters required to calculate Q value were obtained from the site. Based on the obtained values, rock mass is classified and subsequent supports are provided from Q1993 support chart and a comparison of supports is provided by these 2 systems.
