New Austrian Tunneling Method Mean?
The New Austrian Tunneling Method (NATM) is trenchless tunneling method in which the rock and soil of the bore, the supporting formations, are formed into a supporting structure for the tunnel as the excavation proceeds. Initial support is provided by standard means. This method provides an economic benefit due to the cost and efficiency of the process.
Also termed the sequential excavation method.
Trenchlesspedia Explains New Austrian Tunneling Method
NATM can refer to both a design philosophy and a construction method. In a presentation delivered at the 2004 North American Tunneling Conference in Atlanta, GA, one paper (G. Urschitz and J. Gilder 2004), described the philosophy of NATM as, "the general principle of mobilizing the surrounding ground by developing the maximum self-supporting capacity of the rock or soil."
As a construction method, NATM becomes a construction function method: The tunnel's supporting structures are minimized, using the capacity of the rock or soil surrounding the bore as structural elements to support the tunnel.