Summary

This review describes mine shafts and shaft sinking and is a quick guide to resources on the internet about shaft sinking. It gives some general information about shaft sinking, as well as outlines regulations and guides for designing and building shafts. The review also lists shaft sinking consultants, contractors and suppliers, and gives a brief overview of closure and abandonment of mine shafts.

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INTRODUCTION

To speed you on your way, here is a quick guide to resources on the internet about shaft sinking. Interspersed are my recollections of shafts I have seen and dealt with. There is a relative dearth of solid technical information on this subject via Google, so if you can add more information about your own knowledge, experience, resources, or services, please pass it along to Jack Caldwell.

Before you read my text below, take a few minutes out to see the best presentation I found while compiling this piece. It has magnificent photos and high quality cross sections mostly related to mine shafts.

RECOLLECTIONS

The first shaft I descended was that of the East Geduld Gold Mine in South Africa. I was no more than ten or twelve and what we did was probably illegal. My father was a mine captain, and for reasons I cannot recall had to go underground on Sunday morning. I must have pestered him to distraction, so along I went. Thrilling as always to the headgear that loomed so high, my courage began to flag as we stomped into the metal cage, all rusty and dripping wet. A great clang as the door was pulled closed by two large black guys who smiled a sneak smile at this terrified white boy.

All I can recall of the descent was the noise, the metal, and the water that started as a drip but which seemed to become a torrent as we went deeper, ever deeper: 6,000 feet to be precise. My father delighted in telling me "we are now at sea-level" as we climbed out the cage at the bottom of the shaft. Sea-level-flashing through my mind were those beaches of Margate where we built sand castles on our annual vacation.

There is also a faint memory of a smell. I think it is the smell of the oil skins we wore. Maybe the smell of sweat and grime. I have never smelt it again, but it lingers.

Then into a vast chamber cut in the rock. It was filled with equipment: cocopans, drills, generators, and switch-gears. The air was cold, fuelled by a vast wind blowing from fans and ducts that seemed alive. My father told me the rock was hot and we would "cook" if the fans went out. Many years later I ran the cooling plant on the Hendrik Verwoerd dam, now called the Gariep Dam, and came to appreciate the technology needed to keep big places cool.

As a post-graduate student I did some leg-work for Professor Jennings when he was asked to design the caisson needed to get through the first fifty feet of loose sands that overlay the bedrock where a new shaft was planned for a mine in Welcome. On a cold but sunny Saturday we got the pile auger to advance some shafts - about 36 inches in diameter and down through the soft sands. We set up the tripod intending to descend into the shafts to profile the soil, trying to recall the things to observe. The mnemonic was MCCSO: moisture, color, consistency, soil type, and origin. But we never did go down the holes. A quick glance was enough to establish that the groundwater was gushing into the hole and the sand, thoroughly liquefied, was storming in. As Professor Jennings remarked: "That's good information; now we know why we need a caisson."

So we designed the caisson. Somewhere I still have the notes and printout from a primitive computer code I wrote to calculate the stresses using Boussinesq's equation. (As an aside, that site has masses of equations for almost anything you can think of. Another site with masses of equations that are potentially useful to the mining engineer is efunda. Don't forget InfoMine's Find a Tool.)

Construction of the caisson began. It slid down smoothly and according to plan to a depth of about forty feet, and there it tilted and stuck. Professor Jennings, Mike Gowan, and I flew down on a second sunny Saturday. We descended to the bottom of the caisson where all was clean and fresh-smelling of new concrete. But it was obviously stuck. We walked around trying to look impressive and knowledgeable, but we were secretly baffled. In a profound and sonorous voice, the professor declared that he needed the weekend to think about it and he would phone on Monday with a plan of action.

As we exited the caisson, Professor Jennings turned to the construction foreman and in a casual, off-handed way, remarked: "Pity it can't be done, but all that is needed is a case of dynamite to go off where this thing is stuck!" We flew back to Johannesburg.

On Monday, eager to hear the professor's solution, we crammed his office. Coffee cups barely in hand, we heard his secretary announce a call from the mine. Elation and delight swept the professor's face. The news across the wires: the caisson had begun to move early Sunday morning. A case of dynamite was missing from the store and there was a bit of a mess at the bottom, but otherwise no reasonable explanation why it had begun to move again. No matter, in a few days it hit bedrock and conventional shaft-sinking began.

The lesson learnt: hire an expert to design and construct your shaft.