The Art of Tunnel Engineering: Eurotunnel, Mont-Cenis and Mont-Blanc Tunnels | Documentary

drilling entire mountains digging a

tunnel

under the sea Civil

engineering

feats that shatter all records three sites are revolutionized working underground like the 19th century monsignor driving a

tunnel

through a huge mountain whose rock is incredibly hard has never been done before , but it is made possible thanks to a completely new invention, we have a compressed air drill, a kind of descendant of the chipping hammer. The performance is a quantum leap in drilling, however, 140 years in the tunnel must be expanded and a completely new challenge for engineers and continue the walls to collapse the answer is a machine that excavates with centimeter precision the laser checks the markers and It tells the machine exactly how deep and how wide it has to dig another destination long considered impossible: a tunnel under the foreign English Channel like Notre Dame Cathedral was built 800 years ago.

It seemed like a big gamble to dig just 40 meters below the seabed and still avoid the risk of flooding the site. The solution is impressive. It's not just a tunnel. The result is a world first. The longest underwater tunnel on Earth. A tunnel. in the Alps holds another record in 1965 The Mont Blanc tunnel is inaugurated as the longest road tunnel in history 50 years later it also achieves the record of being the most technically advanced of its type there are a thousand sensors that made engineers rebuild a work of more than 50 years what type of machine was needed to replace entire sections of the tunnel it was a colossal effort unique in the world the old slams were cut out, taken outside and then the new three examples of high-end

engineering

were placed with unequal challenges of the most spectacular sites, whether oceans or mountains, we have always strived to overcome the obstacles that nature has placed in front of us.

Tunnels have been among the first great achievements of our ancestors. The gallery was excavated by miners forty thousand years ago, either in the Stone Age.

tunnels

or the latest technological feats, there are hundreds of sites of this type around the world, but the most spectacular of all, which has been in the focus of the international media and accumulated all kinds of records, is the tunnel under the Canal de la Mancha in 1994 for the first time. The British and the French meet without having to get on a ship or a plane. The American Society of Civil Engineers classified the Eurotunnel as one of the seven wonders of the modern world.

Being able to get from coast to coast in 35 minutes was a dream conceived long ago. 200 years ago, in 1801, the French engineer Albert Matthew Favier imagined a tunnel with chimneys 80 meters high to allow in fresh air. An unrealistic proposal in view of a maritime area with potentially complicated climatic conditions. The end of the millennium before the project ends. Considered feasible in 1981 the governments of France and Great Britain give the green light four proposals are under scrutiny one is a gigantic bridge with hundreds of stays another option foresees a combination of tube and bridge but both parties agree on the tunnel a project of 15 billion euros the work will begin on December 15, 1987.

Abroad, test drillings were carried out on the seabed to analyze the different geological layers. Samples taken from several tens of meters indicate that there is a layer of rock about 50 meters below the channel bed. the characteristics are decisive to dig a tunnel it is called chalk Mall Ed millions of years ago when dinosaurs still walked on Earth it has two peculiarities it is comparatively easy to dig and it is impermeable the path of the tunnel therefore has to follow this layer since just above it there is great shock which is much less dense, while great coast consists of 10 clays, the proportion in short Mal is 25, so it is less porous, but there is another danger if the miners dig too deep and they will collide with a layer of the so-called golden clay which is to be avoided at all costs.

The golden clay is a little muddy and very soft. If the rotating Shield Digger had sunk into that layer, the entire adventure would have ended right then and there, so maintaining the exact route is paramount, the tunnel will run at an average depth. 50 meters below the seabed, if they get too close to the surface, millions of liters of water will rush out in a matter of minutes, meaning miners will have to follow the oscillations of the chalk. The excavation of Mar Lair under this premise does not pose any specific problem, but the ups And on the downs of the lair it is foreseen that special trains capable of lifting their weight for a longer time, unnecessary trains that can tow trailers with 32 moving trucks or More than 150 cars at each crossing will set a record in the field of tonnage transportation.

At that scale, engineers have to create new traction motors exclusively for the tunnel, they designed high-powered locomotives with six motors and planned to have a locomotive at each end of a train, meanwhile, work has unfortunately started before Before the actual tunnel can be dug, they must prepare. two huge vertical entrances for the colossal Shield rotary excavators in Britain on Shakespeare's Cliff in France in Sangat Once completed a rather exceptional machine can be lowered into each of them the Shield rotary excavator is an invention that defies normal dimensions a technological monster When moving the factory, it tears from the rock, removes the rubble and supports the walls at the same time.

It is a Swiss army knife 250 meters long, so large that its pieces must be assembled little by little. In the shaft inside the Colossus there are checkpoints for Engineers and technicians to monitor the foreign monster. The Steel Giants will excavate from both ends of the planned tunnel. Their shields weigh 50 tons each and are armed with two rows of dents, one of tungsten placed on top of the other dents that weigh 80 kilograms thanks to this ingenious device, the excavation, will advance at a rate of 3 meters per hour; However, this performance must be achieved three times, as three separate

tunnels

have to be dug, one for the line from France to Great Britain, another for the reverse direction and a third for maintenance.

What they need are three rotating shields on each side of the tunnel and as the machines have to be replaced due to wear and tear there are 11 excavator shields in use at the end a mass of Steel and Machinery that exceeds the total weight of the Eiffel Tower 10,000 tons, but they do not limit themselves to excavating these masterpieces of technology, they more or less build the tunnel themselves, relays of wagons transport the rock from the ground to the base of the shafts, where they are reduced to mush by giant centrifuges, huge rotating blades and , as the chalk crumbles, all you have to do is add water until the entire mass is liquid enough and can be pumped.

Millions of tons of chalk are distributed a little further away, outside the pits, it is a huge amount of material that on the English side caused the most peculiar phenomenon we expanded Britain we created an area of ​​land called Sapphire which is now a nature reserve Birds Plants Etc. everything is land obtained from rubble from the interior of the tongue 30 hectares of new land Sam fire The hoe is twice the size of the largest stadium in France. Efficient rock removal is one of the great advantages of a rotary Digger Shield. However, the moving factories produce another essential element: they are responsible for the installation of busoir, they place separate sections that when welded together will constitute a watertight tube.

Thousands of them will form the mantle of the tunnels on both the English side and the British side. French, several square kilometers are needed to store them before fixing. Underground, thank you, but between the plates and the chalk there is a gap of between five and seven centimeters. It does not sound spectacular, but if water seeps into these cavities, the resulting pressure can endanger the stability of the tube there were teams whose only task was to inject concrete into these holes to secure the tunnel. This protective mantle has been an important axis of maintenance since specialized workers continually plug any crack that may appear with hundreds of trains rumbling through the tunnel.

Water seepage is what engineers fear most. Up to 400 trains pass through there every day. In view of hundreds of passengers and thousands of tons of goods, measures to keep the tunnel watertight are essential, so when work began, the possibility of a significant influx of water caused much concern; Some sections of the tunnel required special attention. The engineers knew very well that there were faults in the Rock at the transitions between sea and land. These were the weak points, one on the British side and the other on the French side. Behind the Burgues, thousands were injected. of liters of concrete in addition to small cracks of five centimeters there are cracks that require repair filling of several cubic meters as long as the three tubes follow the hard, waterproof layer of Mall chalk, there is little or no risk of flooding the tunnel, but what What if there is a rupture in the Earth's crust?

Seismic monitoring is carried out by There are hundreds of sensors inside the Bourgeois, but so far the tremors beneath the canal have been so small that they are practically undetectable. However, if there is a problem within one of the tubes, the engineers have a bypass, in which case it can be passed from one tube to another. the other so that traffic is not interrupted throughout the tunnel the engineers have planned two giant crossings inside the tunnel eight kilometers from the English entrance and 12 kilometers from the French side are these immense cathedrals the crossings there a train can be diverted from its tube and enter the second tunnel a railway crossing under a monumental vault is nothing unusual on the surface, but building one under the seabed is a challenge a French engineer Jacques Ver

mont

finds a solution and proposes building a huge Casco to regroup the two tunnels.

It had never been done before. Six 200-meter pipes are dug and then filled with concrete to solidify them together. They will form a semicircle. It is made up of overlapping mini tunnels. Once the hull is complete, all you have to do is dig. the cave underneath to join the tubes was another historic first, but the crossings are the only links between the railway tunnels. Other tubes are needed for maximum exploitation every 375 meters. These are the so-called piston relief ducts that join the rails they serve. To evacuate the air that accumulates in front of a train coming in the opposite direction, you are inside a tube 7.8 meters in diameter, so if a train reaches 150 kilometers per hour, an enormous compression of air occurs, This air is pressed into the other tunnel through the otherwise the speed of the train would be greatly reduced and speed is key to the entire project.

Trains have to run at 150 kilometers per hour to reach a frequency of 400 trains per day, which adds 26 million tons of cargo each year. It's another world record. However, to ensure that constant maintenance is paramount, the carriages that transport trucks and wagons are large in size and, as each train is 800 meters long, monitoring its sensitive points requires a building of appropriate proportions at 870 meters, It is the largest maintenance site ever seen. Tunnel trains are inspected twice. As often as on conventional railways. Network maintenance and security are top priorities for undersea travel after six years of work. The work is almost complete in December 1993.

The two teams are only 100 meters from each other, the French rotating Shield Digger is stopped. Hundreds of pieces are dismantled and removed from the tunnel. The British have opted for another solution. Their colossus turns to the right and is immobilized forever, but one last question remains: the excavations on each side in a row and what if an excavator? The shield went too high in the 1990s. GPS cannot help in this step. No satellite signal is strong enough, so British engineers send a probe. A telescoping pole pushes its way through the rock. Finally, after several dozen meters, the progress they have achieved occurs.

We found the French tunnel in the place where we were, only 40 centimeters away, on December 15, 1993, at 12:12 minutes Philippe Cozette shakes hands with his British counterpart Graham Fagg the images spread throughout the world The longest underwater tunnel in history is completed today. Its users are 85 Britons. The Eurotunnel is a physical link between France and Great Britain. Its construction has become a reference point in engineering, but there was a precursor that 150 years earlier changed to always tunnel construction technology the monsigni tunnel in the alps retains a special place in history in the 19th century it seems like a huge gamble how to drill a huge mountain of more than 13 kilometers six times the length of avenue de los Campos Elysées in Paris, a tunnel that crosses the Alps to link France with Italy is an impressive proposal, the obstacles are literallyimposing, but the commercial rewards promise to be astonishing, since, for a view, the powers that be opt for the morien valley, it is one of the alpine valleys that link the city of Lyon with the industrial north of Italy, Milan, Turin, etc The best option for trade through a tunnel is to transport goods first by train.

However, some political peculiarities must be taken into account when work began in 1857. The duchy of Savoy in the western Alps remains a possession of the kingdom of Sardinia, one of the many states. which will soon constitute the future Italy, that is, work began on a territory that was 100% under Italian control and only after Savoy was ceded to France in 1860 can we speak of a proper French part. It is unique to have a project that begins in one country and ends up divided between two people of different nationalities, a political mess that does not favor the acceleration of work, the miners take more than 15 years, especially because they have to dig by hand, they achieve 40 centimeters per day, which is extremely slow, the slow progress also The result of a complete lack of knowledge about the type of rock miners encounter is soft, hard and porous.

Today conditions vary constantly, even before work on a tunnel begins. The geologists recognized the environment using probes that were excavated in a tunnel. small previous gallery to see what will be found then there was surprise that almost each layer if the rock turns out to be too hard there is only one way to advance to blow it up, but to resort gunpowder was full of dangers at the time the workers still had a lot to learn it is a very risky job they faced all kinds of imponderables there were dozens of fatal accidents because gunpowder causes rock falls that slow down the work the vault natural has a tendency to sink or collapse completely the excavation is progressing at an agonizing pace contemporary Specialists estimate that it will take at least 30 years to complete the tunnel.

Exasperated British merchants who were eager to transport their goods overland to northern Italy had a surprising idea: they proposed building a railway through a sunnier location 2,000 meters above sea level, while the canal. Still under construction The Martini Railway Company intends to operate a regular train Unfortunately the long climb is often blocked by snow or avalanches of loose rocks reducing speed to a crawl. The company costs investors several million pounds in the end it is a financial investment. The disaster is also largely due to a technological revolution. A local engineer, German Semelier, has invented a device that will be a milestone in tunnel construction.

The ingenious new tool is based on the use of compressed air to power a drill. It will transform underground work for decades. XIX century. The drill resembles a harpoon, measures between three and four meters long and drills into The Rock to speed up work that, as some said, would never end. The sommelier provides the drills with unprecedented percussive power and also obtains the necessary energy directly from the tunnel environment. Its abundance of water from diverted mountain streams pumps air into watertight pipes thanks to an automatically closing butterfly valve. The air is compressed and stored in huge cylinders.

The air can be sent to the drilling rigs through a system of ducts when The valves are closed, opened, the air is shot through the pipes into the tunnel where its energy is released and powers up to four drills at the same time with a pulse of 50 beats per minute. The machine is capable of drilling holes of several dozen. centimeters deep which the miners then insert their explosives, so the detonation will occur deep in the rock rather than on the surface of it. A much more efficient way to blow things up. The sommelier's machine allows us to advance several meters each day.

The new technology shatters all existing excavation records. The new method has a price: the multiple explosions cost the lives of more than 50 workers. In places like this, security was non-existent back then. Working conditions are aggravated by clouds of dust that return to the tunnel after each explosion. The dust penetrates. in the lungs and the blinds the workers no one can endure this for long the sommelier must adapt his machine and he does so with another brilliant solution to use the compressed air to drive fans in order to improve the air in the tunnel the engineer also inserts small openings in the machine itself that allow air to pass through and thus clean the work space of dust now the miners can continue at a much more stable pace the tunnel construction schedule is considerably reduced the sommelier's invention is shortened by almost half the allotted time of 30 years The tunnel was inaugurated in 1870.

It is a feat. The cause causes a stir throughout Europe. Only the contractors of the Sunny Railway company are not joining in the jubilation because their tracks have been made obsolete by compressed air due to the tunnel trade between France. and Italy advances construction will be a success for more than a century with the arrival of the new millennium but deep modifications are needed thousands of heavy trucks between France and Italy calls for an alternative solution in general trucks are not very welcome in the Alps valleys their escapes pose a major problem in maintaining traffic through the Alps the powers that be decide to put the trucks or their containers on the trains a splendid idea except the tunnel is too low enlarging it is a daunting prospect increasing the size you have to Raise the Vault or lower the base platform before large trains can pass safely through the tunnel.

The current foundation needs to be dismantled and the option of cutting the walls and roof removed seems problematic. However, the tunnel may simply collapse. Excavating the ground is easier said than done. How do you lower the foundation enough and provide a safe bed for the new rails? A machine capable of doing that does not yet exist, which is why in 2007 a French company invented an extraordinary tunnel boring machine, the D. Rocker, with a weight of 50 tons and a wheel equipped with solid teeth. The D rocker is an extremely efficient device. Its front part bites into the rock and excavates the ground, but before releasing it the ground must be prepared with one of the tracks are completely dismantled the rails the ballasts the sleepers once the path is clear the rocker D can continue with its work .

It is guided by lasers that keep it on the track and also transmit data about the ground ahead. It moves at a speed of between 40 and 60 meters per day to prevent the Wheel from overheating. The teeth are sprayed with water. The debris is transported to the rear. From the Goliath, the debris is removed by a conveyor belt, thus thousands of cubic meters of materials are evacuated and the platform is lowered 70 centimeters in the 13.6 kilometers of the tunnel. In 2011, the first trucks arrive at the platforms that allow the transportation of your freight by rail. Every day more than 30 trains enter the Monsignee tunnel, but one problem remains unsolved: the tunnel does not meet modern safety criteria safety has become a major concern in the transportation sector an inevitable decision the monsoni tunnel has come to an end it will be replaced by the most modern tunnel ever built to link León with Turin a 57 kilometer section will be built excavated underground the equivalent of 285 high speed TGV trains lined up one after the other it is a tunnel of exceptional length and It will be just below its predecessor, it crosses the same Alpine massif, although it is 800 meters deeper.

The future tunnel is intended for goods and passengers. Work on the train begins in 2016. It is supposed to be completed in 2035. It will have everything that the tunnel lacked. 1870, as ventilation shafts to deal with the worst case scenario, a fire in the tunnel, and will serve to keep one of the tubes smoke-free and bring fresh air to the other tube, which can then be used as shelter for passengers, the Pets themselves require cutting-edge technology, first the teams drill a hole a few centimeters in diameter from the surface to the bottom. In the tunnel, a telescopic arm rotates a cross-shaped device fitted with teeth in the cavern below. the cross and then moves upward as the loose rocks fall to the bottom.

From time to time the drilling has to be stopped to remove the debris for the workers. This is the most critical path, therefore a diameter of 4.3 meters can be achieved. There will be three more wells closer to the first. There are not many people in the world capable of doing so. To do this type of work the new tunnel will relieve the old The underpass was completed in 1870. 20 tunnels will keep the route as the first crossing through the Alpine massif, but not far away there is another legendary tunnel that turned out to be a completely new challenge for engineers, since it was intended for exclusive use in cars and trucks.

It had to be much larger than a railway tunnel, but would it be possible to drill a solid or a tube 10 meters high and 8 meters wide? In the late 1950s no one could say it was a real adventure, we didn't know what we were doing. d encounter once inside the mountain project to break all records the longest road tunnel in the world a quantity of explosives never before used with newly developed drills to reach the planned height and width 1950 work begins the new passage through The Alps reflects the boom The economy of the 1960s before, any crossing of the Alps was a real expedition with horse caravans and creaking carriages, with the Industrial Revolution and the expansion of international relations, but the Alps became a real problem for the exchange of goods, even before working on the 11.

The one kilometer tunnel can begin its journey has to be fixed and since there was no GPS then it means resorting to triangulation to produce an imaginary straight line with the peaks of the surrounding mountains as landmarks, so there is only one way and that is up there, on the mountain. guides to help surveyors The campaign to obtain the necessary measurements took several

mont

hs, not just a few days, and often the weather conditions were not at all favorable at 3,500 meters above sea level. Mountaineers and surveyors take great risks to establish the direction of the tunnel, two guides lost their lives drilling the highest massif in Europe with its extremely dense and hard granite.

French engineers develop a special machine, the jumbo, a huge mobile scaffold weighing several hundred tons and allowing 25 workers to operate 16 drills at the same time. Its percussive power allows explosives to explode. It will be placed four meters deep inside the Rock, the button is pressed and the debris is removed. Over the next 44 months, the jumbo jets on both the Italian and French sides will drill more than 400,000 holes, one thousand two hundred tons of explosives will be transported, they will detonate inside when digging a tunnel, water is a recurring problem, we are talking about 1,000 liters per second.

Sometimes the water comes from a glacier just above in spring the streams of melted ice can become waterfalls at certain points but it is a problem. Engineers have planned that the tunnel will have horizontal obstacles that will cause the water to flow. Without these slopes, miners will be engulfed by thousands of cubic meters of water, but the constant humidity undermines the stability of the tunnel walls, even if they collapse on top of the workers. Engineers decided to install Russian concrete sections that will form a protective tube inside the tunnel, but with two kilometers of rock above, additional precautions are required.

They placed a kind of iron roof with steel plates that prevented it from collapsing. It was a fairly new concept. The Vault was literally nailed to the walls with its 235,000 bolts. This system of consolidating the surrounding rock allows the miners to continue without having to fear a collapse of the Vault, but the further they go, the harder it becomes to breathe. The problem is solved by leading large corridors over the future traffic tube that will bring fresh air from the entrances. This installation is still in place today 50 years ago. Five giant 2.8 meter diameter fans at each end of the tunnel provide a flow of constant air thanks in 1960 the system is much less sophisticated, however, after three years of tunneling, the French and Italian miners find themselves just a few meters away on August 14, 1962, at 11:31 a.m. , they shake hands after having blown up the last granite blocks in the two sections of the tunnel.

The alignment of the tunnel was almost perfect. The deviation from the theoretical axis was just 13 centimeters. Three more years are needed to complete the retention work to cover the rails and install thesignal system on September 15, 1965 the first cars entered the tunnel each year hundreds of thousands of cars and trucks pass through the longest tunnel of its time, considered an emblematic link between two nations until one fateful day, the 24th March 1999, that day at 10:47 a.m. a Belgian truck enters the tunnel. His shipment of margarine catches fire. Driver. is forced to stop the heat is equal to that of a tanker truck on fire at 10 54 the alarm is raised the toxic fumes spread through the tunnel claiming 39 lives the cause is quickly determined the 1965 air system is disastrously insufficient it must be to solve it to date the fire forces engineers to review the knowledge of several decades of tunnel construction the Mont

blanc

tunnel will remain closed for three years the Franco-Italian company that manages the tunnel is embarking on nothing less than a rethinking of the entire thanks project in terms of technology and surveillance is a totally new tunnel the analysis of the fire focuses on the problem of the smoke, how to extract it as quickly as possible, regardless of where it is located along the 11 kilometers of the tube, the engineers They decide to create aspiration points at regular intervals thanks to the fans found in the tunnel, the fumes will be expelled into traps, then sucked through airtight ducts under the streets and evacuated to the nearest exit.

The system algorithms allow the fans to activate in both directions. There are four thousand sensors distributed. throughout the tunnel providing the control center with thousands of data in real time one of the most monitored is the opacity of the air as it indicates the presence of smoke there are additional ventilation systems at the tunnel entrances their function is not to counteract the consequences of a fire but to anticipate a climatic characteristic of the mountain you have to be careful if there is fog on one of the peaks you have to avoid entering the tunnel to guarantee the visibility of the drivers, as well as the air, throughout the entire route.

The construction of the 60s is under constant surveillance for this. 11 kilometers of fiber optics have been installed on the road surface. It is ultra-sensitive and registers all movements in the coating. Any deterioration of the cable causes a degradation of the signal and based on the quality of the signal we can know the exact amount of deformation exactly a signal interruption means that the road surface is no longer stable and must be replaced, but how Are entire stretches of road of various shades each replaced without stopping traffic for days? engineers had to invent an unprecedented machine it was a colossal undertaking unique in the world we had to extract the old sections bring them out of the tunnel and then install the new ones do not tune at night in a 600 meter stretch of the tunnel the lining is lifted from its base six centimeters deep in the floor then the sidewalks and gray plates that cover the walls must be removed.

The Special Machine taken out lifts a six-meter two-ton plate, then turns it, places it on a trailer that then leaves the tunnel returning to the place that is the most critical part, it must not break or hit the walls and then it receives a new section of road and lowering it to the gap is a process that enjoys worldwide recognition, especially because traffic in the tunnel can continue without interruptions on average we have 1,600 heavy vehicles per day increased but for safety reasons circulation is limited we do not allow a random flow of traffic we have a system that sets the Cadence of a vehicle every eight seconds which is the time a car needs to travel 150 meters at 70 kilometers per hour, thus ensuring safety distances to discourage those who like to step on it and do not respect the 12 minutes assigned for a Crossing.

There are six Radars inside the tunnel, they also calculate the average speed of each car, those that exceed the speed limit will face the police stationed at each end of the tunnel the Mont

blanc

tunnel with its 200 cameras and heat sensors at its entrances have become one of the safest underground constructions in the world. Rarely is a model for the 2004 European directive regulating safety procedures in tunnels. However, the regulations for the tunnel do not end there. New technology will be implemented. It's called a platoon. Before you imagine it. Imagine four or five trucks followed quite closely at a distance of about 10 meters, the one in the lead, which we call the pilot truck, will direct the entire convoy, the trucks will communicate with each other but there will also be data with the tunnel. about dangerous loads for drivers or about compliance with the mandatory rest and even about the tire pressure of each vehicle, the tunnel will monitor everything that enters it.

The inventions serving the Montblanc tunnel are scrutinized around the world as Elon's latest creation. Musk a railway tunnel with a vacuum inside and without oxygenation with an air cushion to avoid all friction so that the train, free of all resistance, is destined to circulate at 1,000 kilometers per hour in France, a testing ground has already been built of 300 meters to evaluate similar projects. Technological evolution still seems to have a long way to go. If these projects will see the light and change our daily lives, it is because their precursors have paved the way with incredible feats, such as crossing the Alps for the first time, inventing machines never previously seen they dug the martini tunnel linking France and Great Britain setting the record for the longest underwater tunnel the Eurotunnel has been a success since the longest road tunnel in history was dug through the highest mountains in Europe the The Montblanc tunnel has become a reference work of its kind, a witness to the ingenuity of civil engineers and their willingness to overcome any obstacle.

They will continue to serve as a link between people and as spearheads of innovation.