TECHNICAL | MUSK BORING COMPETITION
the jacking system is said to provide forces of up to 500kN; in discontinuous mode (used only as a back-up) this increases to 1MN. In their research, the team members had established that 500kN would be sufficient to tackle the soil in Las Vegas. Spoil removal was achieved by an auger conveyor allied with conveyor belts integrated into the pipes used to create the tunnel structure.
SWISSLOOP TUNNELLING Founded in late 2020, the Swissloop team was the official team of ETH Zurich and comprised over 40 students. Their expertise spanned mechanical, civil and electrical engineering, as well as various business- related fields. Some of the team members had also participated in the SpaceX Hyperloop Competition of 2018/19 and then, as now, had won second place and received the award for innovation. The distinguishing feature of Swissloop’s ‘Groundhog
Alpha TBM’ was the lining system which allows the in situ fabrication of the tunnel structure. The concept involved a 3D-printed, 15mm-thick tunnel wall made of glass-fibre lamellas and a two-component polymer mix to ‘ensure structural integrity along the whole length of the tunnel’. Lining is created continuously with excavation, with 16 hydraulic cylinders bracing against the tunnel wall for an uninterrupted movement under a propulsion force of 200kN. The 7m-long, 0.56m diameter TBM featured a
cutterhead as part of an ‘erosion system’ with a cutting wheel that extracted large stones. These are subsequently crushed to centimetre-wide pieces and flushed out of the chamber in a slurry under 10 bars of pressure, assisted by a Venturi vacuum pump. Pushing off from the newly-created tunnel wall is achieved by two discontinuous hydraulic grippers. Weighing around 2.5t, the machine was capable of achieving a torque of 8.5kN, rotating at 27rpm and had a 100kN pushing force. Steering was provided by a hydraulic ‘hexapod’ system comprising six hydraulic cylinders that are designed to gave six degrees of steering precision. The machine’s target speed was 1cm/sec.
Top:
TUM Boring steering module
Above: Swissloop cutterhead The technique is claimed to have several
advantages, including fast tunnelling feed rates, robust pipe segments with pre-installed driving surfaces, and considerable use of off-the shelf components. The laser-guided, hydraulically-steered machine
had a fairly conventional water-cooled, motor-driven cutterhead with auger. Propulsion was provided by a jacking system involving two clamps each powered by four hydraulic cylinders. In continuous mode,
46 | November 2021
UMD LOOP The UMD Loop team comprised more than 50 engineering, maths, computer science and physics students – all undergraduates – from the University of Maryland, US. They were not new to such events, having competed in SpaceX’s Hyperloop Pod competition in the past and came fifth; upon graduation, some of the students were hired by companies such as SpaceX, Tesla and NASA. Nevertheless, designing a tunnel boring machine was a totally new experience. Entering these competitions is not cheap, particularly
for a bunch of college students: the TBM alone cost around US$200,00 to design and build, and travel costs for the students from the East Coast to Las Vegas was in the region of US$20,000, paid for through sponsorships, crowd funding and the generosity of the University of Maryland.
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53
