Tunnel lining repair
Introduction
A tunnel is a linear underground work that connects two points for the transportation of people or materials. It is usually artificial.
A tunnel, or lower bridge, can be used for pedestrians or cyclists, although it is generally used to give way to traffic, motor vehicles, a railway or a canal. Some are aqueducts, built to transport water (for consumption, for hydroelectric use or for sanitation). There are also tunnels designed for communications services. There are even tunnels for the passage of certain species of animals. Some connect conflict zones or have a strategic nature, since they serve as a refuge, such as Cheyenne Mountain.
In large cities, transportation is carried out through a network of tunnels where the subway (Metro (transport system)) moves. The possibility of undergrounding saves space and prevents pedestrians or vehicles from crossing at the same level of the train.
History
The origin of the tunnels and the corresponding construction techniques must be sought in mining, an activity of which there is notable evidence already in the Neolithic, such as the Caves of Can Tintorer") in Gavá (Catalonia, Spain). In ancient times, in Assyria, Phoenicia and Israel there are some examples of tunnels that allowed communications and favored the defense of a besieged city. The Asmodean Tunnel"), under the Rock Mosque in Jerusalem would be a example. The Romans had already built numerous small tunnels associated with mining and water transportation (the canals have a very low slope and immediately required tunnels and aqueducts). An example is the tunnel built under the hill of Posilip") to bring the Aqua Claudia to Rome, which was used for twenty centuries. [1] Later, the use of gunpowder allowed the excavation of more important sections. During the 16th, 17th and 18th centuries, many tunnels were made, especially to allow the transport of goods in canals. In general, these are tunnels with a rectangular section of more than 50 m². With the appearance of the railway, and given that it also requires very steep slopes, strict conditions, tunnels began to be excavated for this new means of transport in the . The first railway tunnel in the Iberian Peninsula was the Montgat tunnel in 1848, opened by the route of the railway from Barcelona to Mataró.[2] During the , new tunnels continued to be opened for railways, canals (now more linked to the production of electrical energy) and finally for roads.