Tunneling is one of the oldest forms of engineering found in today’s world. From ancient times man has been creating structures called tunnels in intact rock and soil in order to
achieve a certain purpose. Despite its ancient origins , tunneling in the modern era has taken a drastic step and is slowly advancing into an engineering marvel. Hypersonics are defined as speeds which are far greater than the speed of sound (approximately 5 times). The ratio of speed of a given wave to that of sound is denoted by the Mach number, which in the case of hypersonic waves is around 5.
Such a phenomenon is studied actively in aerospace fields, where hypersonic travel is the subject of interest. However , in the past few years a few companies have utilized this technology to drill holes and tunnels in the Earth’s subsurface with a large amount of success.
One of these companies Hypersciences Inc. , a Texas based startup has succeeded in utilising hypersonics for tunneling at extremely high speeds. Elon Musk’s “The Boring Company” is also moving in this direction. Hypersciences , founded by Mark Russel , who utilised his family’s experience in mining and
drilling, along with his own in Aeronautics and aerospace technology to create several patents on hypersonic drilling technology.
How their Tunneling machine(HyperBreaker) works is as follows-
The machine consists of a power source capable of generating a small explosion within the machine which launches a cement projectile at hypersonic speeds into the rock mass, along with the conventional parts of a TBM(Tunnel Boring Machine) i.e the drill ,drill rods, drill
bits and machine body.
Two distinct phenomena responsible for rock failure take place here-
The first is when the cement projectile interacts with the rock mass. Due to its high kinetic energy , the projectile explodes at the surface creating a small crater in the rock.
The second is the impact the shock wave generated has on the rock mass. This shock wave is what causes a sonic boom to take place. Shock waves are nothing but pressure waves,
which in this case undergo repeated compression with each other due to the object which is traveling hypersonic speeds. Now, this shock wave starts expanding as the projectile
travels. After the projectile creates the crater , this shock wave interacts with the rock
surface thereby fracturing it even further and causing already pre-existing cracks to grow
much larger. This rock mass is now extremely fragile and can be drilled through easily using
conventional Tunnel Boring technology in order to enlarge the excavation.
This new technology has been proven to not only create a 10x increase in advance through
rock , but also cost 2 times less compared to conventional machines.
With such technologies, creating hyperloop tunnels within the earth will no longer seem a
long shot,but a reality.
-Karthik Menon