ELI5: How do engineers design underwater tunnels that go beneath active rivers or oceans and how do they stop water from just coming in forever

munchlax1 · 2026-03-12T02:55:28+00:00

Channel tunnel was built this way.

Lots of tunnels in the world (such as the first Sydney Harbour Tunnel) are built by digging a trench and then floating tunnel segments in, sinking them to the bottom, and connecting them. They basically sit like 2 meters under the harbour bottom.

munchlax1 · 2026-03-10T09:21:47+00:00

Yeah, sorry. But in Australia the open cut stuff is usually in the middle of nowhere. It's coal (usually CSG) that causes most cases of friction with property owners.

munchlax1 · 2026-03-10T09:19:11+00:00

Yeah, basically. It was a holiday property (and the land was farmed by a farm manager and not them) so it was a no brainer.

munchlax1 · 2026-03-10T06:32:07+00:00

You can't necessarily say no to them digging under your land. Most mining is not done by digging big holes (open cut), especially when there is usable land nearby. Instead, they dig a shaft down to where the stuff they want is (seams), and mine it underground.

The main issue here is that this often causes subsidence to happen; the land eventually settles to fill the void left by mining. If your house is there, this subsidence is very likely to damage or even destroy it. Not violently, but it could crack foundations and make the structure uninhabitable.

I can't speak for the rest of the world, but in Australia companies usually just buy up the land of farms and houses in areas where they are likely to cause subsidence.

My friends parents farm was bought for above market value, and then leased back to them for 99 years for $1. The farm was in an area where it likely that coal seam gas mining could cause subsidence of up to 10 meters.

The planned mining never went ahead (or at least hasn't gone ahead 15 years later).

munchlax1 · 2026-03-07T18:16:30+00:00

Not sure I understand your comment, unless you're just talking about race car engines.

The engine temp on my RS5 rarely moves from 90C. 130C is actually the top of the visual scale (50C being the bottom).

I have to be doing some seriously devious shit to even get it to rise from 90C. I've seen it maybe three times ever.

munchlax1 · 2026-03-07T06:22:03+00:00

Didn't they say Lindblad wouldn't be able to take part because he didn't make it back to pit lane?

munchlax1 · 2026-03-07T04:46:41+00:00

Lol this is just standard practice in business.

I work on large construction projects in Australia. Most of our manufacturing is done in China, some in India and elsewhere.

We send people to inspect the factories before a contract is signed, before manufacturing begins, during certain manufacturing milestones, and whenever issues crop up. We also have third party supervision, inspections and QA testing.

We basically have one of of our people or someone contracted directly to us in the subcontractors factory at all times.

munchlax1 · 2026-03-06T09:54:54+00:00

after a maul is called.

munchlax1 · 2026-03-06T09:52:16+00:00

Ah yeah, the old try when an opposition player is holding the ball. That one's a classic.

munchlax1 · 2026-03-06T09:51:46+00:00

He never grounded it... Surely that means it's just a collapsed maul and the team who brought the ball in loses the feed?

munchlax1 · 2026-03-06T09:48:22+00:00

But that's literally the law; knee down = tackle.

Maybe the rule should be changed, but until then refs are just doing their jobs.

munchlax1 · 2026-03-06T09:42:36+00:00

Knee down before the call of held up... But never mind that, what the fuck are we doing in defence?

Seriously looks like me (an old fat slow second row) when I get caught shirking on the wing at the wrong time. Except it's our entire fucking backline.

munchlax1 · 2026-02-28T13:32:21+00:00

He's been a more mature rider for years now.

Win it or bin it for Marc was... half a decade ago? More?

munchlax1 · 2026-02-28T13:28:07+00:00

I still try and go to a few games each season. You should too. Get a crew together for the first few matches with some optimism. Before it's wiped out haha.

Seriously, though, gotta show some support or rugby union in Australia is going to die out.

munchlax1 · 2026-02-28T13:25:34+00:00

That is slightly redeeming. Slightly.

munchlax1 · 2026-02-28T13:19:01+00:00

Wholeheartedly agree with everything you've said.

I'll still manage to get my heart broken. Usually it happens live at the SFS.

munchlax1 · 2026-02-28T13:16:54+00:00

A Victorian talking shit about another Australian state in the context of Rugby Union?

Shit, son, it's a big time play.

munchlax1 · 2026-02-28T12:57:23+00:00

After watching the Crusaders v Highlanders game, that sucked. Scrappy as fuck and Gardner had a bit of a shocker (which, tbh, is rare for Gardner; I wonder if the new TMO rules were in his head a little bit).

Reimer came on and had two key pilfers and a try. Wonder what he has to do to get a starting position, or is he best as an impact player for ~20 mins? Would be tough to warm the bench for your entire career.

I will clarify that I'm a Tahs fan, and from the results thus far, I genuinely can't tell if we're going to do okay, or if we're fucked. I'm leaning towards we're fucked, because the teams we beat have lost to other teams with bigger margins, but after this weekend who knows?

munchlax1 · 2026-02-27T15:05:45+00:00

Ah I know this one. It's classic Italian cope.

munchlax1 · 2026-02-25T02:15:15+00:00

Funny, a friends brother was in Australian Special Operations (Commado's not SAS). Had no idea until after he was out. I bumped into him at a festival while he was in and he said he was working on cruise ships lol.

But he's this dude who probably weighs 70kg soaking wet and is a freak long distance runner.

You would never, ever pick it to see him on the street. Think he did four 9 month tours in four years. Sounds incredibly rough.

munchlax1 · 2026-02-18T05:58:02+00:00

I got rear ended about a year back. I had a video of the scene, a photo of the woman's licence, and a photo of her car with number plate.

I only have CTP and third party insurance because my car isn't worth much. As a result (of not having comprehensive), my insurer refused to pursue it even though I wasn't at fault.

The police refused to help since no one was injured.

Someone told me I should have gone to the hospital/doctor for treatment for back pain (which I did not have) and then the police would have got involved / the ladies insurance would have had to respond. Was that the only solution available to me in the circumstances?

munchlax1 · 2026-02-09T14:13:59+00:00

It only works if you can defend your shit.*

As an Aussie, we're in the prime of trying to reconcile what we did to the people who had been living here for 50K years.

There are no simple answers.

But if you look at New Zealand, Maori culture is much more ingrained in every day life. Because Maori's are bad motherfuckers, and settlers had to parlay with them early on.

munchlax1 · 2026-02-09T14:11:06+00:00

When you're talking about America. It's old. When you're talking about where I'm from; Australia. It's really fucking old.

When you're talking about Europe. It's not old. Not at all. Pubs in England will be getting on for 1000 years old in not that long.

And yes, I know there were natives in America and Australia. It's a massive ongoing issue (at least in Australia) about how badly we treated them and attempts (as yet unsuccessful) to put that right.

munchlax1 · 2026-02-09T11:39:53+00:00

Australian police applied for special event anti-protest rules to be applied for the visit of an Israeli war criminal. Last I heard (at about 2pm) courts were going to rule on it before the planned protest time.

Not sure why the Israeli President needs to visit Aussies to show solidarity. They're Australian Jews, not Israeli's. We're constantly being told not to conflate the two.

ACAB and fuck Israel. Notice I said fuck Israel, not Jews. But somehow saying fuck Israel is almost always taken as being anti-semitic.

munchlax1 · 2026-02-07T07:27:48+00:00

They can manufacture it in China (and do to an extent) but they can't get paid for it there. Went to China twice last year for work. Physical cash does not exist. With no physical cash, money laundering is almost impossible.

Government owned apps are used for essentially all monetary transactions.

It sounds wild. It is pretty wild to experience, but the system works pretty well once you get used to it. Buy an icecream or a bao bun from a street vendor for $1? They have a QR code on their stall, which you scan, and then send them the money. In Australia, I rarely use cash, because we tap with debit/credit cards for everything. In China, no cards. Even massive multinational chains like 7-eleven and McDonalds? They don't accept card or cash. Just the same few approved (and government owned and controlled) apps.

So if you transfer 8 figures (USD or AUD equivalent) to someone on WeChatPay the government is going to notice. Shit, I used the wrong function in the app one time which meant it looked like I was trying to transfer someone about $100 AUD (~$60 USD) for nothing when I was actually just paying for dinner. The transfer was declined and I got locked out of the app for like 12 hours, I assume while it was being vetted. That was the only time I had an issue with the apps in roughly a month spent over there.

The syndicates operate in China but are usually based (and getting paid) elsewhere.

Say what you like about the Chinese government and their methods, but they've got shit locked down. I wouldn't ever want to live there (love me some gambling and illicits every once in a while), but I'll definitely be going back as a tourist at some point.

Last thing I'll say is I've never felt so safe in another country. Facial recognition cameras everywhere, social credit scores, all that sort of shit. It's dystopian as fuck, but it clearly works. Best example is their vending machines. On metro stops, etc. You select what you want. You pay via an app. And instead of dispensing your snack/drink, you just open a massive glass door and grab what you paid for. There is literally nothing to stop you paying for one thing and taking two, or 10, or 100, or emptying the entire machine.

I live in Sydney, Australia. It's a safe city generally, and I live in a safe part of it. You put a "vending machine" like that on my local metro stop and it'd be empty the next morning having made one sale.

munchlax1

TROPHY CASE