ABSTRACT
Underground support in tunnels is probably the largest area of shotcrete use worldwide. There are more international conferences and publications on this topic than in any other area of shotcrete use. There are over one thousand publications on this subject in International Conferences such as Engineering Foundation (now Engineering Conferences International) Shotcrete for Underground Support publications (14 in the series), Norwegian International Symposium on Sprayed Concrete- Modern Use of Wet-Mix Sprayed Concrete for Underground Support (8 in the series) and Australian Shotcrete Conferences (3 in the series). Other organizations such as the International Tunneling Association (ITA) Working Group 12: Shotcrete Use and the American Shotcrete Association: Shotcrete Magazine, also have many publications on this topic. Discussion is provided regarding the so-called New Austrian Tunneling Method (NATM) (often referred to in North America under the name Sequential Excavation Method (SEM)), which was developed by Rabcewicz and his colleagues in the late 1950s, primarily for tunnelling in weak or squeezing ground, using ground reinforcement and shotcrete lining. Discussion is also provided on the Norwegian Method of Tunneling (NMT) and Q-System developed by Grimstad and Barton, which is primarily used in tunnels with harder jointed rock excavated by the drill-and-blast method, lined with fibre-reinforced shotcrete. Case history examples are provided for steel fibre-reinforced shotcrete lining of Rocky Mountain tunnels and the Stave Falls Hydropower Pressure Tunnels in British Columbia, which used the NMT process.
