Listening to the rock: safety in tunnelling

Arnold Dix, President of the International Tunnelling and Underground Space Association (ITA-AITES)

Arnold Dix, president of the International Tunnelling and Underground Space Association (ITA-AITES), shot to international fame in November after helping a rescue team save 41 miners trapped inside the collapsed Silkyara-Barkot road tunnel under construction in India. The Australian expert in tunnel disasters was recruited by the Indian government when repeated efforts to extricate the miners were foiled by difficult geological conditions in the mountainous Uttarakhand state. The successful rescue of the miners captured the attention of the world.

How did this rescue operation compare with others?

“I’d never seen anything like it before.

Normally, when you have a collapse in an underground environment like this, you are typically dealing with recovering bodies and lessons learned:  what went wrong, how can we avoid it happening again, and are there many people still trapped – in the sense of trapped and dead.

So that made it very different. And it also increased the stress enormously because, actually, when I was called, we did not have a disaster – we had a rescue.

So just understanding that, just getting your mind around the fact that it isn’t a disaster yet, it’s a rescue, and knowing that normally it’s a disaster and knowing that rescues mostly fail… that’s a big mind bend.”

What lessons can be drawn from this experience?

“(It is) making sure we remember that despite how clever we think we are, we are still incapable of supporting the mass of a mountain. So, therefore, our engineering always has to be: how do we deceive, trick or otherwise create a stable environment inside this incredibly massive mountain in a way that we harness the forces of nature to provide a stable environment where there should not be a void.

And I think just keeping that in mind is hugely important.”

Are there any early signs that can act as a warning?

“I am originally trained out of a geology school, and a geology school which was a mining school… And in our work experience, and the work I did as an undergraduate, experienced miners would always say: ‘Listen to the rock. Listen to it’. And, translated, what that would literally mean is: when you are underground, put your hand on the rock, feel it, take time to feel the movement. If you’re feeling uneasy, ask yourself what it is that is making you feel uneasy. I’ve always done that.

So even if I am in a conventionally built tunnel, I’ll always go up to the wall, whether it’s a segment or a rockbolt that is sticking out or whatever it is, and I’ll grab hold of it, and I’ll push myself up against the wall, and just take a moment to sort of take in what is going on.

Then, of course, (in) Silkyara… I spent a lot of my time each time I was underground, which is mostly, going right up to the avalanche zone, attaching myself… literally hands in the rockfall, on the rockbolts, pushing myself against the wall – just feeling what’s going on with the mountain because we were in the middle of a catastrophic avalanche sequence, and a big cavern had formed above the avalanche zone, and I was trying to assess whether it was about to blow again on us.”

So even if these accidents seldom occur, we should not take safety for granted.

“And I think this is probably one of the big lessons learned. We’ve become very good with our tech, we’ve gone very well with our mechanisation, we do really well with our modelling, we’ve got our method statements down pretty pat, we’ve got good tech, we’ve got good explosives, we’ve got good rockbolts, we’ve got good ground improvement technology… we’ve got all that sort of stuff, so we’re moving more and more into that either industrial or almost post-industrial sense of: ‘we’ve got these things tamed’; like: ‘we can just pump these underground facilities out, we know how to do them’.

I think it’s that humility and getting – I know it sounds odd – back to basics, (such as:) ‘is there something wrong, can I feel there’s something wrong, is there something that sounds wrong, is there something not going according to plan?’ And a lesson in this one was: it (Silkyara) had a history of collapses.

When it is not going according to plan, take a breath, have a think: ‘could our model be wrong, could there be something fundamentally wrong about our presumptions for this particular instruction?’ And I think this is one of the big lessons here.”

We can minimise the risk, but it will always exist.

“We’re in the business of: ‘what’s our risk appetite? Is this within the range, are we managing it reasonably from where we are?’ And, of course, this varies from country to country, as well.”

What more can be done to minimise risk and improve safety in tunnelling?

“I think the big opportunity we have at the moment… is establishing some baseline criteria for our workforces. So, if you want to do shotcrete, I want to see competency in shotcrete.

So, I think that in our workforces there needs to be competency, and that is something at ITA we’re looking at… It was something we were looking at before Silkyara …to establish basic minimum global requirements for competency.”

Do you want countries to adopt global standards?

“What I am looking at is that the actual way in which it is taught. Things that are important can vary from place to place. So India can do it different to China that can do it different to America that can do it different to Switzerland… So I don’t mind about them all doing it differently. What I envision is some really basic competencies get specified at the ITA level, and that they can be interpreted however it has to be interpreted for the local conditions.

And already I’ve had discussions with governments and I’ve said to governments – and, for example, India – and said: ‘if I can get you this competency requirement – minimum requirement – at the ITA level, could you populate your training facilities in India for your blue collar workers to get competencies?’ And they have said: ‘yes’.

And another thing I’ve said is: ‘if we do that, can you as a client mandate it in your contracts so that the contractors know in advance that one of the requirements would be a certified workforce, so they can factor that in with their pricing?’

So it’s just getting the whole food chain lined up to offer a better quality deliverable.”