The Italian engineers and employees of Mont Blanc Tunnel “The Jumbo” had baptized it, just like the French: it was The huge excavation system Making it possible to go aside Mont Blanc, with one of the most important and impressive European engineering works ever.
Mont Blanc tunnel, A single gallery and double rice tunnel 11.6 kilometers long that unites southeastern France with northwestern Italy, was inaugurated exactly 60 years ago, July 16, 1965presidents Giuseppe Saragat and Charles of GaulleAnd the next July 19 was opened for traffic.
The giant that the mountains dug
The “Jumbo” was the most striking part of the work: a mobile structure with 100 left mounted on a rail with 16 drills on 4 floors. The experienced holes (each 4 meters each) were filled with explosive, for a total of About 1200 tons and 400 thousand “fly”That is, controlled explosions. A brutal job, compared to what was done for it, for example The tunnel under the sleeve: 50 kilometers with three parallel tunnels at 40 meters below the surface of the sleeve bed made with the automated boring machine tunnel, after a coating in prefabricated councils, it was applied. To make the tunnel under the sleeve, it took seven years against the 3.5 of the tunnel excavations.
Instead, the work of the Jumbo after the war was innovative, even with a more traditional approach: the 16 drilled exercises accelerated the laying times of the offices, which came in up to four meters deep and reached up to eight meters of rocks per day. A record for that time, so that the two groups, the French and the Italian, of complete the work in just three and a half years. In fact, the excavations left in January 1959 on the Italian side and May-June 1959 on the French; The last sprint, which became a member of the two galleries, was performed between May and July 1962.
The work, in which two thousand employees participated, was impressive. Of the Mont Blanc tunnel, about a million cubic meters of rock was extracted, it was then covered with 200 thousand cubic meters of concrete and consolidated by 235 thousand bolts To control the decompression of the rock. But the technological dimension of this work, which is sixty years later, remains monumental, does not end here.
A precision that goes beyond all expectations
There are even more than two thousand meters of rock above the tunnel gallery. Mont Blanc placed enormous problems for everything, Also for external reliefs (fundamentally for the orientation of underground excavations), as well as for creating outbursts of ventilation. Nevertheless, the works were completed with an accuracy that is still exceptionally considered today: a waste of less than ten centimeters on the combination of the two galleries. An only vertical deviationWithout any lateral error, which is now almost impossible from the point of view of Engineering, despite today’s digital technologies.
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