Tunnel drilling the Greek way.... video

[cyprusmax47]

I just watched a video in the local press, showing how they work at the new Tsada tunnel without using a tunnel drilling machine. For sure it is much cheaper than to rent a professional one. How safe it is, only experts can tell me. I would not like to be the digger driver though.



Max

[cyprusmax47]

i forgot to add the article which came with the video, despite the Google translation is very poor due to the fact that the original Greek is also poor.

"At a depth of more than 160 meters, excavations have begun for the opening of the first tunnel of the Paphos-Polis road, 720 meters long, which is being built in the area of Tsada.

Further west between the villages of Kalepia and Polemi, the second tunnel will be built, which will be smaller, 290 meters long. The project engineer at the public works department, Iordanis Nikolaou, said that the project is progressing according to the category of rock mass that is located.

Approximately as he said, two meters are opened every 24 hours since the Greek company carrying out the project works in two shifts. After the opening, the tunnel's underpinnings are needed.

The two tunnels will be eleven meters high and ten meters wide, while at the same time escape tunnels are being opened to be used in case of accidents."

source:
Pafos Live

Max

[PolemIan]

I have a good friend who is a retired construction geologist, in fact was the lead on the geology aspects of the Jubilee line extension in London, which was one of the most demanding tunnelling projects of recent times.

I sent him the link to post him up to date on our local project.

Based on his qualifications and experience on such projects globally, I think he can safely be classed as the “expert’ opinion that Max is looking for.

His observations are below:

“Funny how the untutored automatically denigrate 'lesser' foreigners. As far as I can see, they're doing an excellent job.
The rock is competent enough to maintain its integrity in open cut (witness any number of - close to vertical - road cuttings in the same rock type). The bedding is horizontal (witness the light and dark 'layering' in the tunnel face). It is therefore unlikely to suffer failure along bedding planes. Most importantly, they are working above the water table. If they had to deal with water incursion the method of advance would be completely different. In this case, the exposed advance is quickly supported by arch beams, mesh and shotcrete. They are doing exactly what 'British' engineers would do.”

I’ve left the rest out which are along the lines of don’t resort to public prejudice sweeping generalisations if you are not a subject matter expert.

Ian

[Dominic]

Who was denigrating foreigners? No matter how safe the process, I wouldn't particularly like to sit in a vehicle that is under that much rock and dig into the wall. It doesn't mean I think Johnny Foreigner doesn't know what he's doing. Rather that it would make me claustraphobic.

[cyprusmax47]

Ian,
Interesting that your expert finds the method here risk-free, only because of the short video and without knowing a geological map. Less nice, however, is the insulting way of answering which you on top also repeat twice. Thanks very much.

When I spoke of a" Greek method", I meant that it was a Greek company that got the order for the construction of the motorway and tunnel and not, for example, a Cypriot one.

In fact, the Greek company got the job after their offer was around 86 million euros, in contrast to the Cypriots who asked around 300 million euros.

So I mentioned it would be much cheaper for them to do the tunneling with an excavator instead of using professional drilling equipment, however it takes long time until they will be finished as in 24 hours they only gain 2 meters. (source: Pafos Live)

I personally use a geological map every time before I start a job to find water for a well, which is also helpful for the contractor.

As far as the current tunnel drilling is concerned, it looks like the route is in the so-called Pakhna formation, which includes alternating chalks, marls, marly chalks, chalky marls and arenites.

Attached a screen shot from Geological map of the area which i marked purple where the tunnel is going. Black broken line nearby is a fault line which shows why the largest earthquake in Cyprus in 1953 (6,0 Richter)was in Stroumpi. Hopefully there are no tremors while they are still working on the tunnel.



Max

[Dominic]

Hey on the plus side it got your film more views!

[PolemIan]

Max, they are not not using professional equipment, they are using equipment appropriate for the task and geological conditions. My friend is very well aware of the geology of Cyprus having given many talks and tours on the subject.

Ian

[Dominic]

Max never said they weren't using professional equipment. Just that it wasn't specifically professional drilling equipment. You know, like those big-arse drills we all saw when they were doing the chunnel.

And to be frank, your friend sounded rather pompous.