9
votes
Accepted
How are tunnels dug from two endpoints joined?
The alignment of a tunnel constructed from two ends and meeting somewhere is the middle is achieved via old fashioned surveying methods.
If the tunnel breaks through to the surface, surveying ...
- 9,752
8
votes
Accepted
Tunnel at depth problem
Tunnel Access
To begin, to construct and use a tunnel, it needs to be accessed. Access will be via either a vertical or sub-vertical shaft or a ramp that wheeled vehicles can use.
Shafts may be ...
- 9,752
5
votes
Accepted
Have tunnel boring machines been mass produced? What are the difficulties in mass producing a tunnel boring machine?
One of the main problem with tunnel boring machines is they are required for a specific tunneling job: a certain sewer tunnel, a one off underground rail tunnel, etc. Once the job has been completed ...
- 9,752
5
votes
Accepted
Why are tunnel boring machines not using cone-shaped drills?
Because with a flat head the waste material can be (relatively easily) collected and removed from the cutting face.
With a cone-shaped bit that removal is not so easily accomplished.
Cone-shaped ...
- 16k
3
votes
How wasn't Thames Tunnel flooded during construction?
At the risk of performing a pure lmgtfy, take a look at this page
An interesting quote from that page:
The operation was started in 1825 and was halted a number of times
when the river burst in ...
- 4,259
3
votes
Light frame at tunnels and bridges
Such measures do exist, but they don't always prevent careless drivers from ignoring the measures and crashing into low bridges.
One bridge that I know of has been hit at least 100 times and has been ...
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2
votes
Why culmination points in tunnels?
Laterally circumnavigating problematic bedrock is not always possible or practical for the following reasons:
This can increase the length and cost of the tunnel
The problematic geologic zone may be ...
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2
votes
Why do normal tunnel boring operations not use the dirt (from the boring itself) for reinforcement rather than bringing it from other sources?
With present technology dirt is one of the worst possible concrete additives.
It brings the compressive strength of concrete down to unacceptable levels even at fractions of less than 2%.
Elon Musk ...
- 22.8k
2
votes
What lining design holds better for a tunnel? Spiral lining or cylindrical lining?
I think your question actually might be missing a key difference between the two lining systems you mention. Your top image shows a segmental lining. This lining is constructed using the stop and ...
- 141
1
vote
Building a land bridge across the Bering Strait
Blocking a 50 mile/80 km straight would be troublesome at best, ecologically disastrous at worst.
Realistically, large spans like this would tend to be a combination of bridge, land bridge, tunnel, ...
- 7,148
1
vote
Tunnel lining vs structural support
Tunnel linings come in a wide variety of materials and functions.
Some are just finishing precast panels covering the tunnel structure which could be an elaborate system of tie-back wires, steel ...
- 22.8k
1
vote
Have tunnel boring machines been mass produced? What are the difficulties in mass producing a tunnel boring machine?
Mass produced? Depends what you mean by “mass”
For the channel tunnel they made 5, 5 of such a specific machine is perhaps “mass”...
- 16k
1
vote
Is a granite block tunnel longer lasting than reinforced concrete?
It is possible to use granite instead of concrete in construction (remember that buildings were made out of stone long before concrete was invented), but only in those instances where the structure is ...
- 15.3k
1
vote
Does tunnel lining made of cast iron tubings actually accept all the mechanical loads?
They have done their homework, one hopes.
Many competent dense soils are basically self supporting, like all the caves. Yes there is compact or dens soil behind the cast iron panels to take advantage ...
- 22.8k
1
vote
Accepted
Why do normal tunnel boring operations not use the dirt (from the boring itself) for reinforcement rather than bringing it from other sources?
Regarding the word dirt. It depends on what a person means by dirt. Generally, it is understood that dirt means loose material such as soil or sand on or near the surface of the earth.
In mining ...
- 9,752
1
vote
How are tunnels dug from two endpoints joined?
It is not an easy answer... depends.
Basically, depends on the length of the tunnel.
For a short tunnel, let´s say 5 km, it is just a matter to create a grid on the surface, in top of the tunnel to ...
1
vote
Accepted
Is tunnel boring considered groundworks?
In my experience groundworks refers to the site activity of shallow work in the ground, such as trenches (for foundations or drainage) and slab foundations.
Tunnel construction comes under the term ...
- 3,133
1
vote
What casued periodic waviness in the sidewalls of this tunnel?
The most likely explanation for the waviness pattern is improper drilling and blasting practices leaving toe (the ridges) behind, particularly in the floor of the tunnel. In some case the ridging of ...
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Only top scored, non community-wiki answers of a minimum length are eligible