Tunneling has been a crucial part of construction since ancient times. But, how much do you know about the ways in which it has changed? What developments have come to make immense underground and underwater projects, from the London Underground to the Channel Tunnel to London’s new mega sewers, possible!
Thousands of years ago tunneling was a back breaking process. Ancient societies use their hands, and as civilisation developed, hand held tools to create ditches, dug-outs and tunnels.
One fascinating method of early tunnel digging was the heating of rock and stone, before pouring cold water over it to crack and break the rocks in to manageable and movable pieces. This primitive method of demolition has been developed and made more sophisticated in more recent history.
In Ancient History
One historic method of tunnel digging is known as the cut and cover method. This is a technique for building roads that has been around since Roman times and was even used to help in the construction of the London Underground.
With this new, powerful explosive tool, the ambition of tunnelling projects was almost limitless.
During the 1800s the Industrial Revolution was in full swing. Engineering and building projects were bigger and more ambitious than ever.
Alongside the implementation of dynamite we also saw the development of methods involving steam and compressed air to power drills. These drills were used to bore holes big enough to fit explosive charges.
Not only this, but everyone's favourite tunneling tool: The Tunnel Boring Machine.
Tunnel Boring Machines or TBMs are huge flat faced drilling machines with indentations and teeth to allow the efficient demolition of rock and earth in tunneling.
One of the largest tunnel boring machines in the world is Martina.
The shields worked in Brunel's time by having components that sat both horizontally and vertically. This allowed a worker to remove a plank at a time, dig a little further and replace the plank.
There have been other striking developments in tunneling over the last 50+ years.
Known as the New Austrian Tunnel Method, or, the sequential excavation method is a form of tunneling that was first recognised in the 1960s.
The NATM is different from the old Austrian Tunnel Method because it relies on an understanding of the geological properties of the surface being tunneled in to. With constant monitoring, this is a flexible method of construction that allows room to alter the manner in which the tunneling is executed.