A Review on Application of NATM to Design of Underground Stations of Indian Metro Rail

Abstract

AbstractThis paper describes the advanced concepts used for the underground construction of tunnels i.e., the New Austrian Tunneling Method (NATM) in Indian Metro Rail. Many areas of Indian cities are highly congested and populated. Hence, elevated metro rail construction is not always feasible. Therefore, the Metro Rail system in India is elevated as well as underground also. Underground tunnel construction below highly congested urban area is another challenge in itself. It was constructed by using various tunneling methods. Some most popular methods used for tunnel construction in urban areas are Tunnel Boring machines (TBM), Cut & Cover Method, NATM, etc. The construction of a complete tunnel by using a single method does not only consume more time but also results in uneconomical construction. NATM is commonly adopted on both sides of underground stations for providing a safe opening for TBM launching and outbreaks. It is also used for providing cross-passage between up-line and down-line tunnels. In this paper, the methodology of applications of NATM in Indian Metro Rail is explained. The NATM method has been used to construct all underground metro tunnels in India. A comparative aspect of the construction of an underground tunnel by using NATM in Pune Metro and Mumbai Metro is also discussed in this paper. In addition, challenges like heavy groundwater seepage, application of NATM in soft ground, etc. are presented here.KeywordsNew Austrian Tunneling Method (NATM)Cut & Cover MethodTunnel Boring Machine (TBM)Metro stationsCross passage