Tunnel in the water. How underwater tunnels are arranged (photo). Which method is better

English channel

For two centuries, the “Project of the Century” was the construction of a tunnel connecting England with the European continent. More than 15,000 people from France and England were involved in this masterpiece of engineering art. Through joint efforts and at the cost of nine human lives, the world's longest underwater tunnel was built, which the French call the English Channel and the British call the English Channel. Back in the early 19th century, in 1802, mining engineer Albert Mathieu-Favier hatched plans to build an underwater tunnel illuminated by lamps and with rising pipes above the water. But at that time the plan was technically impossible.

Trial construction

Some time later, in 1856, another French engineer, Tomé de Gamon, proposed his own project for a railway tunnel, but the British were afraid to take this step. This did not discourage de Gamon in 1872, and having enlisted the support of like-minded people in the person of the British mining engineer William Low and Sir John Hawkshaw, he organized the collection of money for the construction of an underwater jumper.

Attempts at construction

In 1880, Colonel Boumont designed drilling machines that began counterwork from the French Sangat and the British Shakespeare Cliff. On March 18, 1883, construction was stopped by the British government due to the risk of military invasion. The next attempt to continue the work was the construction of a 130-meter long trial tunnel near Folkestone (England) in the 20s of the 20th century. Once again, fear of invasion caused the British to suspend work. In the 1970s, construction of the underwater tunnel was resumed again, but was stopped again due to another refusal by the British government.

Finally, in 1986, an agreement on the construction of a tunnel was signed and then ratified between France and England, which made it possible to resume work.

Project of the century

There is no doubt that the epoch-making “Project of the Century” became the “Project of the Century”, provoking numerous financial interstate problems. Satellite observatories helped calculate the exact oncoming path, so there were no problems with the technical execution of the project - the tunnels did not converge by only a few centimeters.

The Channel Tunnel, which is almost 51 kilometers long, is second to the Seikan Tunnel, which is 53.9 kilometers long between the Japanese islands of Hokkaido and Honshu, but is undoubtedly the largest underwater tunnel, surpassing the famous Seikan in its underwater part by about 14 meters.

Their total number is 1,190 reservoirs throughout the country, and the number of tourists who want to see at least one of them amounts to millions annually.

But giant bays create many problems related to movement around the country. Instead of driving from point A to point B, locals have to spend hours winding around the winding roads that skirt the fjords. Such delays are especially noticeable in the winter, when the roads are covered with ice and travel times increase even more.

However, the situation may change with the implementation of an ambitious engineering project to build a floating tunnel under the largest fjord in Europe - Sognefjord, the dimensions of which are truly amazing: 204 kilometers long and more than 1300 meters deep. The project, with an estimated cost of $25 billion, is unique in the world, and its implementation will help reduce travel time throughout Norway from 21 to 11 hours.

Like other fjords in Norway, Sognefjord poses a serious obstacle to travel around the country. The local population living in provincial areas is forced to use ferries or travel for many hours just to get to the other side of the fjord. A floating underwater tunnel can save literally a day to cover this distance.

The idea of ​​implementing a solution to cross the Sognefjord was first announced in 2011 by the Norwegian Public Roads Administration. Since that time, many options have been developed for the design of the infrastructure most suitable for Sognefjord: in addition to a floating tunnel, options for a floating and suspension bridge were considered. can be found all over the world, however, the more expensive floating tunnel has important advantages: it is practically impervious to extreme weather conditions, allows ships to move unhindered, and, importantly, does not spoil the natural beauty of the fjord.

Upon completion, the project will consist of two pipes connecting the Sognefjord from different banks. A series of pontoons on the surface of the water will be able to support the pipes in a floating state, and a set of connecting beams will strengthen the entire structure.

According to Public Roads Administration chief engineer Arianna Minoretti, the driving experience of crossing the floating tunnel will be no different from driving through a regular road tunnel. Even though the structure will be floating, it will not look like a “rubber duck in the middle of a hurricane.”

Despite the fact that an underwater tunnel is one of the best options for implementing movement through the Sognefjord, the final decision on its construction will be made in the coming years, after the final calculation of all costs for implementation and for maintaining the functionality of the tunnel in the future.

Based on materials:

The relief of the earth's surface is not perfectly flat, but is almost always complex, so when laying roads it is almost impossible to do without tunnels. The prototypes of tunnels in ancient times were mines; with the help of this military stratagem one could sneak behind the enemy's back unnoticed and fall on his shoulders. Today's tunnels, for the most part, serve completely different purposes. There are a variety of tunnels, differing in length, location and structure. What is currently the longest tunnel in the world?

10. Laerdal Tunnel, Norway (24,510 m)

In this case, we are talking about a road tunnel that shortens the route from the municipality of Laerdal to another municipality of Aurland (both in the county of Sogn og Fjordane, Western Norway). The tunnel is part of the European highway E16, connecting Oslo with Bergen. Construction of this tunnel began in 1995 and was completed in 2000. At that time, it became the longest road tunnel in the world, surpassing the famous Gotthard road tunnel by as much as 8 km. Above the tunnel there are mountains with an average height of about 1600 meters.
The Lärdal Tunnel has a unique feature - three large-volume artificial grottoes are chosen in it at the same distance from each other. These grottoes divide the tunnel itself into 4 approximately equal sections. This is not a whim of the architects, but the purpose of the grottoes is to relieve fatigue from drivers driving for a long time in completely monotonous tunnel conditions, and here they can stop and rest.

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9. Iwate-Ichinohe, Japan (25,810 m)

The Japanese tunnel connecting the capital with the city of Aomori, at the time of its opening in 2002, it was the longest Japanese railway tunnel until it was overtaken by the Lötschberg tunnel. This tunnel is located 545 kilometers from Tokyo, halfway between Hachinohe and Morioka, and the Chohoku express trains run through it. We started thinking about its construction in 1988, and started it in 1991. The structure was ready for operation in 2000, but the line began operating only in 2002. The tunnel goes down a maximum of 200 meters.

8. Hakkoda, Japan (26,455 m)

The Hakkoda railway tunnel is only a little longer than the previous one. He was a kind of pioneer - before him, there were no long tunnels in the world through which trains could simultaneously move in different directions.

7. Taihangshan, China (27,848 m)

In 2007, a new Taihangshan tunnel was put into operation in China, passing through the thickness of the mountain range of the same name. Before the construction of the New Guan Jiao, it was the longest Chinese tunnel. It became an element of the high-speed railway that connected the capital of the eastern province of Hebei, Shijiach-Zhuang, with the capital of the adjacent Shanxi province from the west, the city of Taiyuan. If previously it took 6 hours to get from one city to another, now an hour is enough.

6. Guadarrama, Spain (28,377 m)

In the same 2007, but in Spain, the longest tunnel in the country, Guadarrama, was opened, which connected the capital of the country, Madrid, with Valladolid. It began construction in 2002, so it is obvious that this was done at a fairly fast pace. This is a rather complex technical structure, which also contains two separate tunnels. Thanks to this, trains run along it simultaneously in different directions. It is especially worth noting that high-speed trains of the AVE system are used here. After the launch of the tunnel, it became possible to get from one city to another in just a few minutes. This was especially liked by tourists, who began to visit Valladolid from the capital more often.

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5. New Guan Jiao, China (32,645 m)

This is China's longest railway tunnel. At the same time, being located, as befits an underground tunnel, it is located at a very decent height above sea level (from 3324 meters to 3381 meters). And all because it is part of the second line of the Qinghai-Tibet Railway, laid in the Guan Jiao Mountains of the Chinese province of Qinghai. In fact, there are two separate one-way tunnels here. This tunnel took 7 years to build, and it was put into operation at the very end of 2014. Trains are capable of rushing through these tunnels at a speed of 160 km/h.

4. Lötschberg, Switzerland (34,577 m)

The Lötschberg railway tunnel is located on the line of the same name passing through the Alps, and it is located 400 meters deeper than the Lötschberg road tunnel. Passenger and freight trains travel through this one of the world's longest land tunnels. It passes under cities such as Bern, Frutigen, Valais and Raron. This is a fairly new tunnel, because it was completed only in 2006, and already in June of the following year it was officially opened. The most modern drilling technologies were used during its excavation, so it was possible to break through it in less than two years. Now over 20 thousand Swiss people use it every week, trying to quickly get to the thermal resorts in Valais.
The arrival of Lötschberg has significantly reduced the amount of traffic congestion in the area, since previously trucks and trucks had to bypass Switzerland, making a large circle to travel just from Valais to Bern. It is curious that in the tunnel there is a source of hot underground water, which the Swiss also do not waste, but use it to heat the greenhouse, where tropical fruits grow thanks to this.

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3. Eurotunnel, France/UK (50,450 m)

This Channel Tunnel is a double-track railway tunnel that runs 39 kilometers under the English Channel. Thanks to him, the island of Great Britain was connected to the continent by rail. Since then, it has become possible to board a train in Paris and be in London in two and a quarter hours. The train stays in the tunnel itself for 20-35 minutes.
The grand opening of the tunnel took place on May 6, 1994. It was attended by the leaders of two countries - French President Francois Mitterrand and Queen Elizabeth II of Great Britain. The Eurotunnel holds the record for underwater tunnels and is also the longest international tunnel. Its work is managed by the Eurostar company. The American Society of Civil Engineers was full of compliments and even compared the Eurotunnel to one of the seven modern wonders of the world.

2. Seikan, Japan (53,850 m)

This incredibly long Japanese railway tunnel also has an underwater section that is 23.3 kilometers long. It goes 240 meters underground, resulting in 100 meters below the seabed. The tunnel passes under the Sangar Strait and connects Aomori Prefecture (Honshu Island) and the island of Hokkaido. It is part of the Kaikyo and Hokkaido Shinkansen of the local railway company.
In length it is second only to the Gotthard Tunnel, and in terms of its location under the seabed it is the leader in the world. The name of the tunnel contains the first hieroglyphs of the names of the cities that it connects - Amori and Hakodate, they are just pronounced differently in Japanese. The Seikan Tunnel became the second underwater railway tunnel after the Kammon Tunnel in Japan, and it connects the islands of Kyushu and Honshu under the Kammon Strait.

1. Gotthard Tunnel, Switzerland (57,091 m)

This railway tunnel, dug in the Swiss Alps, when adding its own length with the length of pedestrian and service passages, will stretch for 153.4 kilometers. At the northern end it exits near the village of Erstfeld, and the southern exit is located near the village of Bodio. The construction of the eastern part was completed in October 2010, and the western part in March 2011, after which it became the longest railway tunnel in the world.
Thanks to its construction, trans-Alpine rail transport became possible, and north-west Italy was able to switch from more polluting road transport to cleaner and cheaper rail transport. Travel time from Zurich to Milan has been reduced by almost an hour. The tunnel was opened in June 2016. The company that controlled its construction, Alp Transit Gotthard, handed it over to the Swiss Federal Railways in fully operational condition in December of the same year, and on December 11 its commercial operation began.

With the increase in the depth and width of water barriers, the cost of constructing underwater tunnels increases sharply and problems arise associated with the lowering and underwater joining of tunnel sections. In this regard, a number of countries are working on various conceptual and technological solutions for the construction of “floating” tunnels.

Located entirely in the water, shallow from the surface (depending on navigation conditions up to 30-35 m), such tunnels are held by a system of vertical or inclined cables, fixed to the bottom of the water barrier, or fixed to pontoons (see Fig. 1.1, d, e) .

At the same time, the length of the tunnel passage is significantly reduced, there is no need to open underwater pits and backfill sections, the connection of the underwater part with the coastal sections is simplified and the cost of construction is reduced. Such tunnels can be built up to 30 km long at water depths of up to 500 m or more.

In addition to the usual permanent and temporary loads, the structures of “floating” tunnels are subject to loads caused by fluctuations in water temperature, currents, ebbs and flows, changes in water density, compression waves from passing ships, the likelihood of a collision between ships above the tunnel, loss of buoyancy, damage to the fastening system, etc. .

Norway has developed a program for the construction of “floating” tunnels through deep fiords (water depth up to 600 m). Individual reinforced concrete sections ranging from 300 to 500 m in length are kept afloat by guy ropes attached to the tunnel structure and in anchor arrays at the bottom of the fiord.

An example is the project for the construction of a “floating” tunnel near the city of Stavanger at a depth of 25 m from the surface of the water in a fjord 155 m deep (Fig. 5.22 and 5.23).

Rice. 5.22.

Of the various options for “floating” tunnels - supported on coastal abutments (with a short length), on intermediate supports, anchored into the bottom of the strait (Fig. 5.24, a) or suspended from pontoons (Fig. 5.24, b) - A Kvaerner-developed steel structure consisting of lowering sections, secured by cables to cylindrical pontoons, was chosen. It can be assembled away from the tunnel route and then delivered to it afloat.

It is planned to build a tunnel through Hogsfjord on the southwestern coast of the country. The width of the fiord at the intersection is 1400, depth - 150 m. The construction of a bridge or a tunnel buried in the bottom in this place is fraught with significant difficulties. Tunnel sections of circular cross-section made of prestressed reinforced concrete with a diameter of 9.5 m will be immersed to a depth of 15-20 m below the water level and anchored with cable guys to the bottom (Fig. 5.25).

Rice. 5.23. Options for the cross section and fastening of the “floating” tunnel near Stavanger in Norway: 1 - tunnel; 2 - water level in the bay; 3 - bottom of the bay; 4 - cable stays

Based on six years of comprehensive design and research work, the construction of a “floating” tunnel under Eidfjord has also been proposed. The width of the fjord is 1270 m, the depth of the water is 400-500 m. The tunnel of prestressed reinforced concrete sections with a diameter of 9.5 m is designed at a depth of 15 m from the water surface and is secured with cables to the bottom, and horizontal braces to the shore anchor devices. A variant has been developed for fastening the tunnel with floating paired pontoons anchored to the bottom. Each pontoon is attached to 24 gravity anchors by means of double 44mm diameter steel cables passed through looped outlets at the top of the anchors.

A three-section “floating” tunnel is designed for the Eiden fjord with a width of 1240 m and a depth of 450 m.

The largest “floating” tunnel (model of the “Archimedes Bridge”) for passing combined road and rail traffic between the mainland and the island of Sicily was designed in Italy through the Strait of Messina. Several tunnel options have been proposed, differing in dimensions, anchoring method, etc.

Rice. 5.24. Options (a, b) of floating tunnels: 1 - tunnel; 2 - anchor guys; 3 - pontoons

According to one of the options, a tunnel with a total length of 3.25 km includes lowering sections made of prestressed reinforced concrete, made in the form of three conjugate circular tunnels with an outer diameter of 12.3 m. The side tunnels are intended for two-lane road traffic, and the central one for double-track railway traffic (Fig. 5.26 ).

With a strait depth of 100-130 m, the “floating” tunnel is planned to be located at a depth of 40 m from the surface of the water for the purpose of unhindered passage of ships. The position of the tunnel sections, which have positive buoyancy, is strictly fixed by a system of paired cables anchored in reinforced concrete masses laid along the bottom of the strait.

It is planned to install three sections of prestressed reinforced concrete on the 2.05 km long underwater section. The sections are equipped with fairings on the sides to reduce the force impact of the water flow. The guy rope system is designed for a tunnel lifting force of 96 thousand kN (300 kN per 1 m of tunnel length) and for horizontal sea current pressures.

Rice. 5.25. Schemes (a, b) of “floating” underwater tunnels under Hogsfjord in Norway (project): 1 - sections of the tunnel; 2 - pontoon; 3 - anchor plate; 4 - cable stays

The main cables are attached to the tunnel structure every 10 m and anchored into reinforced concrete masses at an angle of 60° to the horizontal. Another group of cables for perception of horizontal pressure is attached to the tunnel at an angle of 45°. The tension force of each cable is 1260 kN, the weight of the anchor concrete mass is about 300 tons.

The design of the “floating” tunnel includes emergency compartments that prevent the tunnel from rising by filling them with water (the valves are automatically activated) in the event of a break in one of the cables.

Rice. 5.26. Cross-section of the “floating” tunnel under the Strait of Messina (project): 1 - compartment for cars; 2 - ballast weight; 3 - compartment for railway trains; 4 - cable stays; 5 - anchors; 6 - fairings; 7 - water level; 8 - bottom of the strait

According to another version of the project, three separate tunnels are provided: one for double-track railway traffic with a length of 5.4 km and two for two-lane road traffic with a length of 6 and a diameter of 15.5 km. The tunnels will be secured at a depth of 47.75 m from the water surface using guy ropes.

In Japan, projects have been developed for the construction of “floating” tunnels between the islands of Honshu and Hokkaido, under Uchiura Bay, as well as between Kasan and Kobe airports through the bay in Osaka. Of greatest interest is the project of a two-tier underwater tunnel between the islands of Honshu and Hokkaido through Fuka Bay. The upper tier is intended for two-lane road traffic, and the lower tier is for double-track railway traffic. In an underwater area at depth

The “floating” tunnel is held 20 m from the water surface by guy ropes. To counteract vibrations of the tunnel structure during the movement of trains and cars, as well as from sea waves, fin-type stabilizers are additionally provided.

In Switzerland, three options have been developed for the construction of a transport crossing of the lake from north to south: a bridge, a tunnel constructed using a closed method, and a “floating” tunnel. The latter turned out to be preferable. Ten tunnel sections, consisting of two coaxially located steel pipes with a length of 100, an outer diameter of 12 and an inner diameter of 11 m with concrete filling between them, will be held at a depth of 14 m from the water surface by a system of cables located every 50 m at an angle of 45° to the horizon.

There are also project proposals for the construction of “floating” tunnels across the Strait of Gibraltar and the English Channel, under the Great Lakes in the USA and Canada.

Norway is a country of fjords - narrow, winding sea bays with rocky shores cutting deep into the land. Their length is several times greater than their width, and the banks are formed by cliffs up to 1 km high.

Despite the extraordinary beauty of nature, this complicates transportation. Conventional tunnels on the seabed are practically impossible in many places due to the depth of the fjords, and bridges are difficult to build due to the rugged coastline and steep cliffs.

Then the idea arose to create car tunnels floating in the water column. The first crossings could appear between the cities of Kristiansand and Trondheim by 2035. If the project is implemented, the road along the sea will take motorists 10 hours instead of 21 hours due to the abandonment of ferry crossings.

The project is a hybrid of a tunnel and a bridge, suspended below the surface of the water, but high above the bottom, which can be very deep (the Sognefjord reaches 1.3 km).

Two tunnels - one in each direction - will be located at a depth of about 30 meters. Each of them will be a rigid pipe 26 km long. They will be connected to each other by passages every 250 meters in case of evacuation.

The slope of the tunnels should not exceed 5%. The pipes will be assembled on land, after which they will be immersed in the sea. Water will be poured into several ballast containers so that they sink to the desired depth. The force of the air inside the pipes and lifting them up will be equal to the weight of the containers with ballast, lowering the pipes down. Due to this, buoyancy will be avoided.

The pipes will be held on top by cables attached to the top of the pontoons, and heavy anchors will be attached to the bottom. This way, specialists will achieve complete immobility of the tunnels, ensuring safe driving.

However, for motorists the tunnels will still be classified as high-risk objects. Any incident that would be considered insignificant on an ordinary road can even lead to disaster in a tunnel located inside the mountain. And in Norwegian tunnels there will be 30 thousand liters of water above each square meter of road.

The depth of the tunnel - 30 meters - was chosen so as not to interfere with navigation.

Despite such an unconventional solution, driving in an underwater tube will be no different from driving through a regular tunnel. 1,150 transport tunnels have been built in Norway, 35 of which are underwater, so it will not be unusual for residents of this country to navigate floating underwater crossings. For example, in 2013, the longest underwater tunnel, Karmey, was opened there. Its length is almost 9 km.