Underwater transport tunnels. Norway plans to build the world's first underwater floating transport tunnels

If there are highways on the route large rivers, sea straits or bays, there may be a need to construct underwater tunnels, which in some cases have technical and economic advantages over bridge crossings. Underwater tunnels do not violate the conditions of navigation and everyday life of the water barrier. Low banks of the watercourse, which increase the cost of the bridge crossing due to the need to ensure under-bridge dimensions, are favorable for the construction of an underwater tunnel.

Approaches to bridges, especially in urban areas, disrupt the architectural ensemble and may, in some cases, require the demolition of buildings and structures.

The choice between a bridge and a tunnel crossing a water barrier is made on the basis of a technical and economic comparison of options, taking into account both construction and operating costs.

In some cases, when crossing large water obstacles, it is advisable to construct combined tunnel-bridge crossings, consisting of a low-level bridge and an underwater tunnel on a navigable section.

Typically, underwater tunnels are built under the bottom of a watercourse, leaving a protective soil roof of at least 3-6 m (Fig. 3.4, a).

Rice. 3.4.

1 - underwater section; 2 - ramp section; 3 - dam;

4 - winding sections; 5 - supports

When constructing underwater tunnels in conditions of significant water depth (more than 30 m), tunnels located on artificial dams arranged along the bottom of a watercourse (reservoir), tunnel-bridges and floating tunnels can be used. The design of a tunnel on dams consists of separate ready-made elements - tunnel sections, which are lowered from the surface of the water or moved from the banks along the axis of the tunnel along rails laid along artificial dams, and then joined together (Fig. 3.4, b). The construction of such tunnels significantly reduces the length of the underwater passage, but this requires a significant amount of earthwork for the construction of dams.

An underwater tunnel-bridge is a combined structure in the form of a tunnel of separate sections, supported on supports like pavements (Fig. 3.4, c). Such structures can be constructed at the intersection of very deep watercourses, and the depth of the tunnel is determined by the conditions of navigation.

Unlike bridge tunnels, floating tunnels are held at the required depth from the surface of the water by guy ropes anchored to the bottom.

Approaches to the tunnel - ramp sections - are constructed in an open excavation with a lining in the form of an open structure made of monolithic or precast reinforced concrete, consisting of a tray and side walls of variable height, reinforcing the slopes of the excavation. The length of the ramp depends on topographical, geotechnical conditions and economic factors. In some cases, closed-type ramps of a seamless design are installed.

On March 13, 1988, the Seikan Tunnel, the world's longest underwater railway tunnel, was opened in Japan. Today we decided to talk about it and other most remarkable underwater tunnels that tourists can visit.

The longest

While Chinese scientists are working on the project of the next record holder - an underwater tunnel with a length of 123 km - the longest operating railway corridor on the planet remains the Japanese Seikan. To implement the idea of ​​connecting the two largest islands of the Country by the shortest route rising sun it took 42 years and more than $3.6 billion. The initial time and cost of constructing Seikan was increased either by weak soils, too much water pressure, or endless financial difficulties. And then on March 13, 1988, the Japanese press finally exploded with enthusiastic essays: the train, hidden in the depths of the tunnel in Honshu, rushed under the waters of the Sangar Strait and emerged like a float in Hokkaido. The “majestic spectacle” (as “Seikan” is translated from Japanese) reaches a length of 53.85 km, a little less than half of which is hidden in the underwater depths. The tunnel is equipped with protection from natural disasters and the force of the water element: ultra-sensitive sensors are installed inside that respond to the slightest vibrations of the earth, powerful pumps that pump out up to 16 tons of water per minute, and impressive shelters with sufficient reserves in case of disaster. Now Seikan is not as famous as it was 20 years ago, but is still a landmark in Japan.

The oldest

An interesting fact: the very first “underwater bridge” on the planet was supposed to connect the two banks of the Neva in St. Petersburg. But fate decreed otherwise. The royal customer Alexander I died before the talented architect Marc Brunel completed the project, and his heir Nicholas I was not interested in the technical innovation. The developer decided: let’s not let the goodness go to waste, and turned to another “advanced” monarch - Queen of England Victoria. Here he was luckier: the method he invented, which is still used in the construction of tunnels, was implemented to connect the two banks of the Thames. 50 thousand Londoners gathered to watch the opening of an underwater communication 459 meters long. By the standards of 1843, this was almost half of the capital's population! Although the tunnel never became a cargo tunnel due to a lack of funding, it was extremely popular: walking under the river seemed as incredible as being on the moon. The corridor turned into a city of entertainment: a shopping gallery and an underwater brothel appeared here, and the world's first underwater fair was held. After some time, the passage under the Thames was abandoned: for 145 years only wayfarers looked here. More recently, voices have been heard again in the oldest underwater tunnel in the world: London authorities are conducting walking tours through the historical dungeons.

Photo: usolt.livejournal.com

The most deep

The construction of a tunnel under the Bosphorus, which managed to connect Europe with Asia, was a long-standing Turkish dream that seemed like a fantasy. It took more than 150 years to realize the idea that the Ottoman Sultan Abdul Hamid had back in 1860. The opening of the Marmaray tunnel, which took place on October 29, 2013 and coincided with the National Day of Turkey, was not without incidents: electricity was cut off in Marmaray and passengers were forced to get out of the train stuck in the tunnel. The length of the communication, which unites three underground and 37 above-ground stations, 8 suburban and 4 interchange stations, reaches 13.6 kilometers, with 1,400 meters passing directly under the Bosphorus. The capacity of the double pipe, laid 60 meters below the bottom of the strait, is one and a half million passengers per day, and its safety system can withstand earthquakes of 9 points on the Richter scale. Besides the undeniable economic benefit, which solved the problem of congestion in Istanbul’s transport system, the construction of Marmaray brought another unexpected benefit. During the mega-construction, 40 thousand important archaeological finds were discovered, including a flotilla of 30 Byzantine ships, worthy of a place among World Heritage sites.

Photo: andrewgrantham.co.uk

Most entertaining

Until 1997, a distance of 15 kilometers, ridiculous by today’s standards, did not seem like just an annoying trifle to residents of the Japanese cities of Kisarazu and Kawasaki. Because the shortest distance between these points lay across Tokyo Bay, Kisarazu, which lies very close to ultra-modern Tokyo, resembled a rural outback. After all, to get there by car from the capital, you had to travel a hundred kilometers. Japanese engineers were faced with an extremely difficult task: building a bridge between different sides of Tokyo Bay would impede the movement of sea vessels, and building a tunnel was too problematic due to the instability of the seabed. The technical solution was ingenious: Aqualine was a very successful and safe combination of an underwater tunnel 9.6 km long and a bridge 4.4 km long. But it was not the sensitive smoke detectors installed every 25 meters, nor the latest anti-seismic technology that placed the Tokyo tunnel in this rating. On one of the two artificial islands, through which Aqualine passes, there is an entire entertainment complex similar to a passenger liner. In addition to parking for 480 cars, there are restaurants, souvenir shops, recreation areas and observation decks.

The most famous

Everyone knows about the modern wonder of the world that connected Foggy Albion with the Fifth Republic: the Eurotunnel, opened under the English Channel in 1994, has become a symbol of the unification of Europe. The idea of ​​laying a direct route from England to the mainland came to mind outstanding figures of all times: from scientists of the 13th century to the ambitious Napoleon, who dreamed of sending cavalry under the strait, carrying out ventilation through pipes reaching the surface. And only at the end of the 20th century “Europe finally joined Britain”: three tunnels (two for train traffic and one reserve) are connected in unified system air vents and spare tunnels. In order to reduce the piston effect that occurs when high-speed trains move at speeds of up to 350 km/h, a ventilation system is laid over the tunnels, and refrigeration stations are installed at both ends, cooling the rails. Interesting fact: The British approached the construction of the 51-kilometer Eurotunnel with particular enthusiasm. They dug faster than the French and dug 15 km more. And they treated the land created during construction more romantically, creating the man-made Cape Shakespeare. The disadvantages of the Eurotunnel (for example, high tolls) are compensated by its undeniable advantage: it is the fastest and interesting way travel from continental Europe to Britain.

Norway has ambitious plans to install the world's first floating underwater road tunnels to help travelers easily traverse the nation's many fjords.

Currently, the only way to cross a large expanse of water involves a series of ferries - an inconvenient and time-consuming process.

The "submerged floating bridges" will consist of large pipes located at a depth of about 30 meters, each of which will be wide enough for two lanes of traffic.

The underwater bridges will be supported by pontoons along the surface, connected by metal trusses (a lattice structure that strengthens and supports the floor) to provide stability.

There is also the possibility that the structure could be further bolted to the rock.

Each bridge system will consist of two tunnels, located side by side, for traffic in each direction.

Despite the unconventional structure, officials say the undersea tunnel will be no different from a regular, traditional land-based road tunnel. Today, there are 1,150 transport tunnels in the country, 35 of which are under water.

So why not build a regular bridge? Unfortunately, the difficult terrain in these regions makes it unsuitable for a conventional bridge. The only alternative to floating bridges is a suspension bridge or pontoon bridge over the water, however, these structures have the disadvantage of being susceptible to bad weather. They also interfere with Navy ships that sometimes conduct training in the area.

On this moment Norway allocated $25 billion Money for this project, which is expected to be completed by 2035. Engineers will still have to work on the design for final approval: no one has ever built such road tunnels before, and no one is exactly sure how wind, waves and water currents in the fjords may affect the structure. If the idea of ​​floating tunnels proves too difficult to implement, politicians have the right to choose another project while maintaining funding.

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UNDERWATER TUNNEL (a. underwater tunnel; n. Unterwasserstollen, Unterwassertunnel; f. tunnel sous-marin; i. tunel submarino) - designed to overcome water obstacles for the purpose of passing vehicles and pedestrians, laying utilities, etc. Underwater tunnels, in contrast from bridges do not disturb the watercourse regime, do not interfere with navigation, protect vehicles or communications from adverse atmospheric influences, and when located in a city, they minimally disturb the architectural ensemble. The advantages of underwater tunnels compared to bridges increase significantly with flat banks of a watercourse and with intense shipping.

Depending on the location relative to the bottom of the watercourse (reservoir), there are underwater tunnels buried in the soil massif (Fig., a), tunnels on dams (Fig., b) or individual supports (tunnel-bridges) (Fig., c) and " floating" tunnels (Fig., d).

Tunnels on dams, bridge tunnels and "floating" tunnels are effective when crossing deep water barriers, because... at the same time, the length of the tunnel passage is reduced and the operational performance of the route is improved.

The world's first underwater tunnel (900 m long, 4.9 m wide and 3.9 m high) was built in Babylon under the Euphrates River in 2180 BC. e. Operated around the world a large number of underwater tunnels for various purposes, among which transport tunnels predominate: subway (table).

Underwater tunnels were built under the Moscow, Neva, Kura rivers on the lines of the Moscow, Leningrad and Tbilisi metro, road tunnels - under the canal named after. Moscow in Moscow, under the Sea Canal in Leningrad, etc. It is planned to build the largest underwater tunnels under the English Channel (52 km), the Strait of Gibraltar (32 km), the Gulf of Bothnia (22 km), the Bosporus Strait (12 km), the Strait of Messina and etc.

Underwater tunnels are located on a straight or curved route in plan, which is associated with the need to bypass areas of strong erosion, islands, artificial underwater structures, etc. The depth of underwater tunnels relative to the line of possible erosion is taken to be at least 4-5 m in dense clay soils and not less 8-10 m in non-cohesive soils. With the method of lowering sections, the minimum depth in dense clay soils is 1.5-2 m, and in cohesive soils 2.5-3 meters. The radii of curves in plan and profile, longitudinal slopes and dimensions of underwater tunnels are taken depending on the purpose of the tunnel and its location according to the relevant standards. The width of underwater tunnels reaches 40 m or more, the height is 10 m (for example, in Antwerp).

The method of constructing underwater tunnels is determined by its length, cross-sectional dimensions, topographical, geotechnical and hydrological conditions. Underwater tunnels are most often constructed using the panel method or the method of lowering sections. In some cases, mining or open-pit methods are used, and in difficult engineering-geological conditions - tunneling under compressed air, lowering caissons, dewatering, plugging, artificial freezing or chemical consolidation of soils. The structures of underwater tunnels constructed using the shield method are made in the form of circular tunnel linings made of cast iron or steel tubing or reinforced concrete elements with internal waterproofing. In the mining method of work, vaulted linings are made of monolithic concrete or reinforced concrete. Lowering sections of underwater tunnels can be circular, binocular or rectangular cross-section made of reinforced concrete with external waterproofing. Underwater tunnels are equipped with artificial ventilation, lighting, drainage systems, as well as special devices that ensure the safe operation of the structure.

Representatives of the Norwegian government have announced the start of an ambitious plan to build the world's first underwater floating tunnels, which should make life easier for people who are forced to frequently move around this country, crossed by many fjords, bays with rocky steep shores. Currently, the only way to make such a trip is to travel through a series of ferry crossings, but this is an extremely inconvenient and time-consuming method. “Underwater floating bridges”, which can solve the problem of rapid movement, are huge concrete pipes floating at a depth of 30 meters below sea level, the thickness of which is enough to organize two full-fledged traffic lanes.

The underwater tunnel will be kept afloat by pontoons floating on the surface. Engineers are also considering options for anchoring the tunnel in some places to the seabed, which should increase the stability of this structure. Each such underwater bridge will consist of two parallel pipes, each of which will have two lanes of traffic in one direction. Despite such an unconventional solution, driving inside an underwater tunnel will be no different from driving through a regular tunnel. In total, 1,150 transport tunnels have now been built in Norway, 35 of which are underwater, so it will not be unusual for residents of this country to travel through floating underwater tunnels.

Why didn't the Norwegian government resort to building normal bridges? Unfortunately, the steep rocky slopes and the fairly large width and depth of the fjords make them completely unsuitable places for the construction of traditional structures. A suitable alternative to an underwater floating bridge in this case are suspension bridges or pontoon bridges running on the surface of the water, however, such structures are too susceptible to adverse conditions. weather conditions. In addition, they will to some extent interfere with shipping traffic.

Currently, the Norwegian government has already collected about 25 billion dollars to fund the implementation of this project, the completion of which can be expected around 2035. And this long period of time will be a difficult stage for the project engineers, because such a transport system has never been built in any corner globe and no one knows how the design of an underwater tunnel will be affected by waves, wind, underwater currents, etc. And if the construction of underwater floating tunnels turns out to be unaffordable, then the Norwegian government reserves the right to curtail work on this project and redirect funding to find and develop alternatives.