crossrail: where is it in the list of \'big digs\'?

by:Gewinn     2019-08-26
Tunnel project for New Cross Railway in London
The West rail network is currently at its most tense stage.
The scale of engineering challenges is amazing.
With the cost down, eyes-watering.
Visitors and shoppers at Red Lion Street in central London have little idea what is going on at 30 metres below their feet, although people in buildings with deep foundations may be curious.
2 tunnel boring machines (TBMs)
Ada, named Felix and Ada, is cruising on Earth.
The length of each vehicle is 14, and the weight is 1,000 tons.
The computer display in Felice\'s control room shows that the machine is 18mm lower than where she should be, 27mm too far from the left.
But this is within the design tolerance of 50mm.
\"The 50mm is very small in terms of engineering,\" said Andy ALDE, project manager for cross-rail Western tunnels.
\"When you think the diameter of this machine is 7 m, it is a great achievement to control it within 2 inch m.
\"Europe\'s largest construction project at the moment has been completed in half, has absorbed more than 25 million working hours and produced about 8 miles of tunnels.
Last year and this year, the project supported the equivalent of 13,800 pounds.
Time work throughout the supply chain.
When the project is completed by the end of 2019, the route will start at Berkshire\'s medenhead, extend to Heathrow Airport, and then pass through central London, then head to Shenfield in Essex and Abby Wood near Greenwich.
It will consult corruption within 10 thousand people-
Just minutes from central London.
TBMs have carbide cutters on the surface of the cutting ground, and loose soil is fed back to the machine on the conveyor belt.
What happens to all these pieces? Much of it -4.
5 million tons-
The new RSPB nature reserve will eventually be formed on the island of varancia.
After one has been cut,
6 m ground, pre
The pouring concrete part is transported forward and lifted by the piston to form 22-
Tons of ring around the tunnel ground.
The machine then diverts forward on its 22 hydraulic cylinders, which have pull forces and can lift 2,900 London taxis.
Working 24 hours a day, a tunnel shield can be 100 metres a week.
As it takes 45 minutes to get to the machine from the ramp of Royal Oak, the crew have all the facilities they need on board, including the canteen, office and safety room with emergency oxygen supply.
\"I\'m an underground man now,\" said Jim Gagan, Chief miner at Felice.
\"Although it\'s good to go out and walk during the day, it doesn\'t affect us here when it rains upstairs --
The weather is nice and warm in winter.
Gagan said he was \"pushing up by shoveling things in the back.
His father was also a tunnel miner working in the Channel Tunnel.
According to Mike Black, a top soil engineer and tunnel veteran at cross-rail, the London project is more complex.
In particular, these nine new stations, some of which require a lot of underground excavation, have the potential to replace the soft clay and sand in London.
When TBMs cross the ground, the ground on the palm face is under pressure-
All roads and buildings are monitored around the clock.
\"We have seen sports and we want to see sports,\" Black said . \".
Structurally, the buildings are not affected, but when cosmetic damage occurs, the crossbar will have to pay for the redecoration.
So far, all detected moves are within the prediction range of less than 10mm.
Cross-track engineers inject mud into the soil below the building to fill any gaps that may arise and lift the building back into place.
Underground London, underground tunnels, secret passages, Roman ruins, high
Long voltage cable
The forgotten reservoir and the foundation of the building.
The route through these obstacles winds through, passing only one.
5 m above the North subway line.
On the long table
Before the tunnel construction, the designer carefully checked the yellow plan of the London building.
For some people, they have charts that are actually built.
For others, they just had the initial plan.
The surveyor of the Cross Railway estimates the size of the foundation by checking the buildings.
Then there\'s the bomb.
\"It is estimated that some 17,000 tons of bombs were dropped in London during World War II, and the rule of thumb is that about 10% bombs did not explode,\" said Simon Cook of consultancy 6 Alpha . \".
When some bombs are removed, they cannot be deactivated because they are too dangerous, and other bombs are missed or even abandoned.
Alpha studied records kept by wartime ARP wardens, local authorities, and sometimes even the German air force, to identify areas along the route where there was the greatest threat of explosive ammunition.
Contractors were then sent to investigate the areas separately.
No bomb has been found so far.
However, the engineers of the cross-rail company found some unpleasant surprises.
Plan to use the Victorian Connaught tunnel under the old London pier.
But when divers find that the brick on the roof of the tunnel is separated from only 25 cm of the mud on the Thames, engineers have to give up plans to build the tunnel from.
Instead, the cross-rail built dams to stop the water in the tunnel while they removed the roof and expanded and deepened it.
This technique of digging from the surface rather than from the lateral tunnel is similar to that of the 1870 s.
At the end of the tunnel construction, some tunnel boring machines costing 10 m each will be demolished.
But this would not happen without a nearby axis.
\"Then it\'s not cost-effective to remove the machine underground, and the labor force is risky to do so,\" said Andy Alder . \".
\"So in this case, we will look for buried underground and stay underground forever --
We take out all the valuable parts, but we have to leave the basic shell of the machine underground.
\"Jim Gagan, the chief miner at Felice, feels like he left part of himself underground as well.
\"I can touch the wall, or I can touch the back of a piece of text, and I know I may be the last person to touch it forever,\" he said . \".
You can listen to the quest at BBC World Radio.
The episode on cross-rail will be broadcast at 10: 00 on August 5. 30 -
Listen to or listen to discovery podcasts live.
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