New Austrian Tunnelling Method (NATM)

New Austrian Tunnelling Method Latest News

The Mumbai-Ahmedabad bullet train project recently achieved a 4.88 km tunnel breakthrough under Thane Creek using NATM (New Austrian tunnelling method), marking major progress in excavation.

About New Austrian Tunnelling Method 

• It was developed between 1957 and 1965 in Austria.
• The main idea is to use the geological stress of the surrounding rock mass to stabilize the tunnel itself.
• It is both a construction method and a design philosophy.
• The philosophy looks to use the strength of the surrounding soil to the greatest extent possible to strengthen the tunnel structure.
• In other words, ground conditions drive the tunneling operation. 
• The NATM philosophy also promotes constant monitoring.
• The NATM construction method is about flexibility—drilling and designing depending on the results of the ongoing monitoring. 
• The operation occurs sequentially to take most advantage of the ground conditions. 
• Additionally, NATM installs ground support on the go and on an as-needed basis, adding reinforcement to the shotcrete where necessary.
• NATM is best suited for short-range (> 2 km) tunnels in regions with variable soil conditions.

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Key Facts about Thane Creek

• It is one of the largest creeks in Asia and is located partly on the coast of the Mumbai metropolis. 
• It is an inlet along the shoreline of the Arabian Sea that isolates the city of Mumbai from the Indian mainland.
• The east bank lies in the Thane and Navi Mumbai districts, while the west bank is in the Greater Mumbai district. 
• The creek runs about 26 km north from Mumbai harbour before it joins the Ulhas river through a small channel.
• There are several sources of fresh water for the creek, of which Ulhas river is the largest, followed by numerous drainage channels from various suburban areas of Mumbai, Navi Mumbai, and Thane, making the water brackish. 
• The site is a mixture of saltpans as well as stretches of mangroves.
• Thane Creek is a very important wintering ground for waterbirds. It supports over 1,00,000 birds during winter, including the iconic flamingos.
• A major part of the creek has been declared a bird sanctuary called Thane Creek Flamingo Bird Sanctuary (TCFS).
• It was designated as a Ramsar site, a wetland of international significance, in 2022.

Source: TIMES