Taking shape: terminal building at Mexico City's new airport. Taking shape: terminal building at Mexico City's new airport. milenio

Soil is a challenge in building new airport

'It's very muddy,' says an engineeer as work proceeds to slow the site's sinking

Since Aztec times construction projects in the Valley of Mexico have faced unique challenges because of the lake-covered topography and spongy underlying soil.

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Those same challenges remain today.

But at Mexico City’s new international airport, which is now beginning to take shape, work designed to slow down the sinking of the site is almost half finished.

The biggest progress to date has been the laying of a foundation designed to bring greater stability to the soft earth that was once covered by the waters of Lake Texcoco.

The system is called deep foundation or piling, with vertical piles inserted at depths of four to 11 meters to increase the ground’s capacity to bear the enormous weight to which it will be subjected.

A total of 5,564 concrete piles measuring between 15 and 21 meters long will be used and 2,612 of them are already in place, representing 47% completion of the construction stage.

According to Miguel Solís — a supervisor for Gami Ingenieria e Instalaciones, the company that manufactures, transports and installs the piles — land in the area is sinking at a rate of 1.5 to two centimeters a month, up to 24 centimeters a year, but the deep foundation system will reduce that by 50% and ensure that the inevitable sinking happens in a uniform fashion.

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“The airport is going to continue sinking [but] the piles help to increase the bearing capacity so that the building doesn’t sink as quickly. The concrete slab will work independently, like a boat, without being bound to the piles.  It’s called a flotation system. The terminal building is going to float on the old Texcoco Lake.”

The company is also working on a similar foundation system at the ground transportation center.

The perimeter of the x-shaped terminal building – conceived as an allusion to Mexico — has also been marked out and a 1.5-meter-thick slab of hydraulic cement reinforced with steel is expected to be poured next week over an area measuring 1.5 kilometers by 550 meters.

It was announced in January that a consortium led by Carlos Slim’s construction company had been awarded an almost $4 billion contract to construct the terminal.

Work has also begun on the construction of an air traffic control tower to the north of the terminal building and again the major challenge is preparing the land to bear significant weight.

The ground will be excavated to a depth of six meters where a 65-meter-diameter foundation slab will be placed to support the 90-meter tower.

Abel Casados, an engineer working on the tower construction, explained to the newspaper Milenio that due to the special characteristics of the soil at the site, the excavation will take place in two stages and geotechnical instruments will be used to monitor the behavior of the ground on a daily basis.

Casados added that the water content of the soil “is three or four times more salty than seawater,” which can affect the durability of the piles. So pozzolan and other additives are used in the structures to increase their resistance.

“It’s one of the main challenges of the ground.  This soil is one of a kind in the world.”

Still, he remains confident that the project will be a success.

“It has been questioned a lot but Mexican engineering has all the experience [required] to carry out [the work to meet] all of these challenges.”

The muddy ground is one. “For every soil particle we have three water particles. It’s soil with 300% dampness; it’s very muddy.”

The US $13-billion airport is expected to begin operations in 2020 with three runways and a passenger capacity of 50 million per year before eventually reaching a capacity of 120 million passengers annually with six runways.

The existing airport is struggling to cope under increasing strain from passenger numbers, making the new project vital for the ongoing prosperity of one of the world’s largest cities.

Source: Milenio (sp)

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  • delmaracer

    Good luck with this one.

  • Jack Inmanz

    “The perimeter of the x-shaped terminal building – conceived as an allusion to Mexico”. Figures. Make it an airport easy to get around in? NO. Remind the people who can see the shape of the building that it is in Mexico. That would be the people on the space station.

  • From South of the Border

    As usual you build something in the worst possible place.. Find an area that isn’t so muddy even, if it means longer travel times from the airport to the city itself, but no good luck. I can just see the headlines 10 years from now the runways have buckled and the terminal is sinking fast 13 billion wasted. What a great idea, NOT!!!

  • MortimerSnerd

    Toluca is badly underused, and sits on far stabler ground, but it’s 45 min out of town. Guess this is all about the briefcase carting button-down Suits, politicos and movers n shakers who want to be close to centro when they land… then they sit in bumper to bumper grid-lock traffic for an hour. Been there, done that.

    • EstebanCardenas

      No, its not. Toluca is even at higher altitude than CDMX. Taking off from TLC has a very high weight penalty, which makes it unsuitable for intercontinental operations. So many Americans are so used to look down at MX, that they end up making foolish comments which only show their great ignorance.

      • MortimerSnerd

        Seems Herr Cardenas has an anti gringo slant to his posts… fyi I am Canadian not American…and we welcome Mexicans to Canada… and don’t Visa them out, nor does our Prime Minister call them nasty names. 727… Airbus… regional and North American routee jets are all easily capable of flying out of TLC.. FED-EX have a major hub there. I used to live near the end of the 15/33, a 13,780 ft/4310 m, long runway in the Santin fractionmiento development, and most jet traffice was over a thousand feet in the air passing over the casa. The 8000′ msl altitude of Toluca is no barrier. It’s a badly underused airport with plenty of ‘slots’ available to any international North American carrier that wants to fly to Mexico. As it is many international flights do leave from TLC.

        • EstebanCardenas

          You are wrong, again. Just to begin, 727s are discontinued. Putting that aside, that type of airplane could never reach Europe nor Asia from TLC without intermediate stops.

          Modern airplanes like the 787 could, but with a very high weight penalty, which makes the trip hardly profitable. Air Europa used TLC for services from MAD because they could not get a slot in MEX. They had to discontinue the flight because it was not profitable.

          TLC is appropriate for expansion of national flights. That does not satisfy the need for a major airport with intercontinental capacity + national service to serve as a connection hub.

          Let me extend my original comment: so many Americans + Canadians are so used to look down at MX, that they end up making ignorant comments.

          • MortimerSnerd

            I stand corrected on the 727 (my brother flew one as captain and first officer, and yes they are still in service and may still be used for freight out of TLC) .. typo…meant 737 (their many generations 200 all the way to 800) and Airbus a319- a320 as used by Volaris, AeroMexico, Tucan Air and other regional/international carriers flying out 2000 to 3000 nm.

            There are a lot of freight aircraft. I know Fed Ex has a DC-10 daily flight. Mexican; you have Aeronaves TSM DC9, Convair’s and Metro’s. Estafeta uses Boeing 737’s to and from the USA.

            The new high speed train being built to serve the Toluca/MEX corridor will provide convenient and reasonably priced ground transportation service between the two cities. I would expect the regional carriers to use TLC much more in the future. Ground transportation has always been a problem at airports, where exclusive-operator taxi fares can often exceed the price of an airline ticket. Just look at Puerto Vallarta, wehre it costs $20US just to drive off the airport property in a white ‘Airport Taxi’.

            These aircraft will all operate from TLC, and they dobut the long distance international carriers/European or Asian will find the TLC 8500′ elevation a challenge in spite of the 13,500′ runway length.

  • instead of making it sink at half the rate, why not make it float?

  • Kimberly Fleitz

    Are they out of their minds, or just looking to find a great hole into which to pour money? Only in Mexico.

    • EstebanCardenas

      The project was designed by top international airport construction experts from the Netherlands, the United Kingdom, the United States, and of course, Mexico. Its such a shame they did not consult you.

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