When was the NATM Technique Developed?
In 1848, in Pribram (south of Prague) fast setting mortar was used in place of heavy timber support in a coal mine at Wejwanow. At the same time, a Swiss engineer, Karl Ritter proposed curved tunnel sections with immediate closure of the invert - providing a closed ring in any squeezing ground. This was probably as a result of the 1818 patent of Brunel's circular soft ground tunnelling shield.
In 1907, shotcrete was effectively invented by Carl E Akeley. A taxidermist in Chicago - he developed a machine to spray mortar on the skeletons of dinosaurs to protect them against erosion. The first recorded application of the shotcrete method in the tunnelling industry was in the USA in the early 1920's.
The New Austrian Tunnelling Method (NATM) is often linked to a patent by Professor Ladislaus von Rabcewicz, who invented the duel lining support for tunnels (initial and final linings). This concept, however, had little to do with the application of the shotcrete but merely expressed the concept of allowing the rock to deform before the final lining is applied, reducing the load. The idea behind ensuring the deformation of the rock was based on the theoretical investigations by Engesser in 1881 and was applied by Schmid in 1926.
The original advocate of the use of shotcrete as immediate support in sqeezing ground instead of more traditional heavy timber or steel support was Anton Brunner, a mining engineer from Salzburg, Austria. The 'Shotcrete Method', as NATM was known at the time, gained worldwide recognition when it was applied under the consulting guidance of Professor L Muller and Professor L von Rabcewicz in the Schwaikheim Tunnel in 1964.
The first successful application of the method in soft ground conditions in an urban environment was in Frankfurt/Main in Germany in 1968