How Tunnel Boring Works (2011) [video]

https://www.youtube.com/watch?v=qx_EjMlLgqY

by rkagerer • 7 years ago

73 30 7 years ago

This is how it worked before Elon Musk reinvented it by buying a sewer boring machine and running it dozens of feet under a desert.

anonu• 7 years ago

I'm not sure if your comment is meant to be snarky. But seriously... What is Elon doing differently?

robbiep2• 7 years ago

As I understand it (and I am certainly not qualified in any regard with respect to this type of engineering) he is aiming to increase velocity by decreasing diameter (ie couple meter diameter vs 10m diameter) and then also looking at how they can ‘juice’ the machine using engineering magic

neotek3• 7 years ago

Making promises he can't keep about things he doesn't properly understand to convince well-meaning but ultimately naive investors to keep coughing up the dough, as usual.

jcranmer• 7 years ago

It's hard to give a non-snarky answer because The Boring Company has been very light on actual details, as most of their publicity has focused on the alternative transit method they propose instead of TBM details. Even most of the details on tunneling they suggest aren't meaningful for making it faster; the only one that really is making TBMs run 24/7.

The only reason Elon thinks he can make it faster that I can divine is engineering magic.

DonHopkins• 7 years ago

How do they steer? By using perfectly machined custom segments that turn them in the correct direction?

jetrink• 7 years ago

They touch on that briefly at 8:10 in the video. The rings aren't perfect cylinders; the top and bottom are angled so that each ring is slightly longer on one side. (I.e. They resemble radial slices of a torus.) If each ring is rotated 180 degrees relative to its neighbors, the lengths average out and the tunnel goes straight. If the orientation is kept roughly constant, the tunnel curves in the direction of the short side of the cylinders.

abduhl4• 7 years ago

This is partially correct. This is how the curve is maintained with the concrete liner. Steering is also accomplished via articulation jacks at the head and controlling differential stroke of the main jacks.

It should be noted that only certain types of precast segments work the way that is stated with all rings having an angled face - other types have specific concrete segments for each particular curve with the rest of the rings being planar. This approach has gone away in the industry with advances in software.

sweetcherrypie• 7 years ago

Why is the video unlisted? Very rare for a 1M+ view video to be unlisted.

BigJono• 7 years ago

Interesting stuff.

One thing I was hoping the video would touch on is how do they know exactly where they are and how they are oriented while boring large tunnels? If you're digging 30km of tunnel, being off by half a degree in any direction would be disasterous, no?

abduhl4• 7 years ago

Survey control is transferred down the tunnel from surface. How it gets down there depends on whether you launch from a shaft or pit, but once survey control is established in the hole it is straight forward to locate the TBM using standard survey techniques (eg - survey prisms). The TBM has a reflector that can be shot with a survey instrument to accurately place the machine head and the TBM itself is equipped with gyroscopic or accelerometers for backup control if survey is lost during mining.

Jerry2• 7 years ago

Absolutely fascinating! After watching all that CGI, I wanted to see an actual machine in action and came across this video:

https://www.youtube.com/watch?v=qlrZ3G0tAzY

it's by the company that makes these massive boring machines.

iLemming• 7 years ago

I wonder how software is engineered for those machines. Languages used, etc.

ekianjo• 7 years ago

Not sure if I missed it but how do you bring this kind of equipment underground in the first place? Do they have to dig a huge hole using traditional methods first?

7952• 7 years ago

Yes, they have to build a shaft. One way is a diaphragm wall. A ring of smaller shafts are dug and filled with concrete to form a circular wall. Then the centre of the ring can be excavated with the retaining wall already in place.

anotheryou• 7 years ago

I'm pretty sure they do. I mean after all you often have a ramp in to it anyhow, but I think they also use vertical shafts where they e.g. build a subway station anyways.

rkagerer• 7 years ago

The pipeline video is fascinating, too. They coat the exterior of the pipes with a lubricant, and install new segments at the back end, thrusting the entire line forward each time. https://www.herrenknecht.com/en/products/productdetail/85/?w...

How Tunnel Boring Works (2011) [video]

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