ECN Forum Forums Photo Discussion Forums Photos for General Discussion Puhoi Drill No.1

High Potter,
SH1, is short for State Highway No.1, the main highway that runs the length of the North and South Islands here in NZ.
Alan,
Yes you can, because that is the only thing they work with.
Bear in mind you'll probably need a fair bit of current to melt them, as opposed to your standard rutile rods.

HP - you're part right and part not. Subway construction was ended in LA because a local politition got a law passed making it illegal. However, he's now going to try to get his law repealed, so the subway may eventually head west thru mid-cities again. However, that's not exactly why we're tunneling now.

The light rail line extending from Pasadena to Union Station in LA is being extended thru East LA, and about 1.7 miles of it needs to go underground. Hence twin tunnels. An underground portion of the light rail line does not make a subway, however, even partly. Our subways are heavy rail, and not overhead OCS fed.

Radar

Here are some really big TBMs:
http://www.robbinstbm.com/TBMs/tbms.html

Thanks Mike, and Solarpowered for your replies re SH 1 and the link tio the big tunnel bore machines.

The great part here near Puhoi was, that I had access to the electrical site of it and was allowed to take some photo's of it.

HighPotter The drill arm can swivel up and side wards. In the first stage the upper part of the tunnel arch is done, then the middle, and as last the lower part of the arch.

In the 1980's a tunnel was drilled for the Te Rapa to Tauranga railway, through the Kaimai ranges, this one had a full diametre drill of the actual tunnel bore, the remains of that machine are still dumped at the eastern entrance to the tunnel.

The plan is for 2 tunnels approx 10 * 14 Metres diametre, what the on site guys told me.

How long are the tunnels going to be?

Alan,
Sorry to be ambiguous about Hard-Facing rods.
You need about 130-150A to melt a Hard Facing rod, not exactly the thing for a DIY welding set, at any sort of duty cycle.
As I said above the normal rutile rod takes little current and you can work with a short arc, not so with a H/F rod.
Bank on a 1/2" arc at the least, with a very slow travel, penetration is what counts, that is the most part of Hard facing.
If you don't have the penetration, you might as well be using hot glue, it'll fall off like it too.

Just a follow up here.

Today 01 Mar 2006, I was back at the tunnel to collect two dataloggers from one of the transformers, to check for voltage sags.
the worst readings were 220 Volts ( about 4% under Unom. is 235 Volts ) at low speed at the 500 kVA spare transformer.
The feeder trip was recorded also and lasted for 10 minutes, Auchh!!

At the moment they are not allowed to drill at full speed, 1500 RPM because of the D.O.L. start will take out the feeder.
An engineer will try to sort ou the trip settings on the local switch to the 1000 kVA transformer, while off loading branch lines from this feeder is looked at by the lines company at the moment.

I had a look in the tunnel which is about 20 metres inwards in hard rock.
Arc is about 12 metres wide.
The drill is manned with 2 operators.
The swivel part with the drill extends about 6 to 8 metres from the machine and does the breaking of the rocks, very noisy and clouds of dust.
The water cooling jets are not being used at the moment because of low speed operation at 750 RPM, although the drill bit ran a lot slower, more like 2 to 3 revolutions per second. still a lot of heat is generated though.

The tunnel is supported in 5 metre sections, The drill operator is not allowed to work in the unsupported area of the tunnel, hence the swivel option and extendable drill shaft, works in the unsupported area of the tunnel.
The machine can be remotely controlled, in case of dangerous unstable rock area's and camera's provide the information.

As soon a 5 metre segment is cleared of rocks, steel guirders are inserted, to support the tunnel roof.

I forgot my camera, but the dusty conditions were far from ideal anyway to take a good photo. An other site visit will happen in the near future and hopefully conditions are better then.