Tunnels and large underground spaces
Since its foundation, our company has been committed to a narrower field comprised of geotechnics, geotechnology and mining in planning the construction of tunnels and large underground spaces.
According to the modern definition, a tunnel can be any underground opening with two exits, a surface of minimum 20 m2 and optional length. In the past, tunnels served as transport paths, which is still their main task. Tunnels were constructed manually until 1680, when blasting with gunpowder was used in France for the construction of the 160 m long tunnel of the Canal du Midi channel. Mechanical excavation was first used after 1930, while TBM technology, which actually means drilling of the whole tunnel profile, was first used in 1954 for the construction of directional tunnels of a dam in South Dakota, USA.
Today, besides the development of various excavation techniques, there is also a parallel development of new theoretical bases and various planning methods through which it is possible to relatively accurately foresee the behavior of hill surroundings of the tunnel and at the excavation front. The success of these predictions largely depends on estimated geological and geotechnical conditions in the broader area of an individually planned object. This fact separates underground objects from other construction objects, because the hill medium is in many cases unpredictable and its behavior during construction may be different from that predicted.
The construction area of underground objects includes planning of other groups of underground spaces that are installed under the surface in various hills (caverns, energy stations, warehouses, public objects, shafts that are intended for connecting the surface and other target underground objects). In recent years, the most often implemented method from among all conventional planning methods for constructing underground spaces around the world has been the NATM (“New Austrian Tunneling Method”) method, which is also called the injected concrete method. It combines modern excavation and supporting technologies and other technological construction processes, including geological and technical observation, before, during and after the construction of an underground object.
NATM is discussed in two important documents, namely Austrian Standard ÖNORM 2203-1 and the Guidelines for geomechanical planning of underground activities with cyclical excavation progress and primary support issued by the Austrian Society for Geomechanics - ÖGG. Our company successfully uses NATM for planning of underground objects in all design and execution phases.