In contrast to the cut-and-cover method, the New Austrian Tunnelling Method (NATM) is a mining technique that was first used in 1955 when building a tunnel for an Austrian hydropower plant.
The focus of the NATM in on taking advantage of the inherent geological strength available in the surrounding rock mass to stabilise the tunnel.
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Firstly, the ground is drained using walls and secured using so-called steel plates, spears and steel tube screens. The tunnel is then sequentially excavated and supported metre by metre by applying shotcrete to steel arches and lattice girders.
Extensive geological knowledge is required for this method, and it is necessary to measure tension and pressure shifts in the rock on a continuous basis.
Today, the NATM is the most dominant tunnelling method used around the world.
