A team of students from ETH Zurich and other universities has taken second place in a tunneling competition hosted by billionaire business magnate and entrepreneur Elon Musk.
The team, named Swissloop Tunneling, also won the competition’s Innovation & Design Award for their 2.5-ton tunnel boring machine, which leverages a 3D printing mechanism to simultaneously fabricate a supportive tunnel lining while the tunnel is being dug.
Musk’s Not-A-Boring Competition
Musk has long held an interest in 3D printing, with the technology at the core of his ambitious plan to transport more than a million people to Mars over the next few decades. Musk founded his private space exploration program, SpaceX, in 2002, which has since flown a 3D biofabrication facility to the International Space Station (ISS) and launched a 3D printed high-throughput satellite to orbit.
In the summer of 2020, Musk’s Boring Company announced a tunneling competition focused on building small-scale tunneling machines capable of digging a 30-meter stable tunnel with a diameter of 50 cm. More than 400 teams applied to take part in the competition, with 12 finalists, including Swissloop Tunneling, invited out to Las Vegas to put their inventions to the test.
Reinforcing tunnels with 3D printing
The competition took part in the Nevada desert, and saw the 12 teams embark upon digging their tunnels before being interrupted by a heavy thunderstorm and sandstorm. After working through the night, Swissloop Tunneling was one of just two teams cleared to carry on the dig during the final round.
The team deployed its 7-meter 2.5 -ton Groundhog Alpha tunnel boring machine for the dig, and managed to dig a tunnel more than 18 meters long. The team was beaten only by competitor TU Munich, although neither team were able to dig a full-length tunnel during the competition.
The Groundhog Alpha was also the only machine capable of fabricating a supportive tunnel lining in-situ, thanks to its 3D printing mechanism. Using the mechanism, the machine applied a specially-engineered polymer mix to the tunnel wall which hardened immediately. Meanwhile, two hydraulic grippers worked alternately to press against the newly created tunnel tube in order to propel the machine forward continuously.
The supporting material consists of tough fiber glass materials and a two-component polymer mix, which was 3D printed to create a 15 mm thick tunnel wall. The material ensured structural integrity along the whole length of the tunnel, and was awarded the competition’s Innovation and Design Award for its performance.
Going forward, the Swissloop Tunneling team hopes to further develop the technology to enable the Groundhog Alpha to dig tunnels with a four-meter diameter. This is the width of the tunnels required for Musk’s SpaceX Hyperloop competition, which is seeking to build high-speed capsules to travel through vacuum tubes.
ETH Zurich’s innovation in construction 3D printing
In addition preparing for the tunneling competition, ETH Zurich’s researchers have been carrying out multiple construction projects using 3D printing technology.
In July 2020, they developed a novel “eggshell” concrete 3D printing process that fuses robotic large-scaled FDM 3D printing with casting methods. The technology enables the construction of complex concrete structures in a more material-efficient way.
In the past, ETH Zurich has also leveraged 3D printing to create a five-ton 3D printed curved shell concrete pavilion and has combined 3D printers and robotic arms to digitally fabricate a three-storey house.
In the last few months alone, the organization has announced plans to build a 23-meter high tower made up of 3D printed columns for a cultural site in Switzerland, and has successfully created the first 3D printed self-supporting concrete footbridge alongside Zaha Hadid Architects, concrete 3D printing specialist Incremental3D, and building materials firm Holcim.
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Featured image shows Swissloop Tunneling’s Groundhog Alpha tunneling machine. Photo via Swissloop Tunneling.