EDUCATION | R&D
learned from participating in the competitions – not only in technological terms but also with regard to the organizational arrangements within the team. In the end, these invested efforts also turned out to be
very successful. In the latest ‘Not-a-Boring Competition’, held recently in Bastrop, at the end of March 2024, Swissloop Tunneling achieved great success by winning the overall competition; after reaching 2nd place in prior competitions, the team and the technology gained the ‘Champion Award’ for 2024. This recent success is also proof that ‘Groundhog Beta’ has essentially progressed towards the vision of being used in the real world.
ENGINEERING: ‘GROUNDHOG BETA’ The technical features of Swissloop Tunneling’s current MTBM, ‘Groundhog Beta’, consists of the following: Erosion: As opposed to the ground conditions in Las
Above:
The comprehensive work around the machine gets supported by strong elements above the ground
geology, and business administration students have
responsibility to manage the partnerships and public communications. Finally, an interdisciplinary team of students with the
highly valuable support of industry representatives and institutions was ready. The team has since grown. More than 100 passionate student members of the university have already participated at Swissloop Tunneling over these first years.
ENGINEERING: ‘ALPHA’ TO ‘BETA’ Within a year of its founding, in 2020, Swissloop Tunneling had invented, developed, and tested its first micro TBM (MTBM), named ‘Groundhog Alpha’. The MTBM was taken to the first ‘Not-a-Boring Competition’, in 2021, in Nevada. At the competition the MTBM and team did well; they won the award for Innovation and were placed 2nd in the overall competition. This participation was a first notable success along the project’s journey. While maintaining the strong approaches of the
Alpha model, the Swissloop Tunneling team decided to implement new subsystems and renamed the updated machine to be ‘Groundhog Beta’. With these new systems, the MTBM successfully participated in the 2nd edition of the ‘Not-a-Boring Competition’, held in Bastrop, Texas, in 2023. At this competition, the team once again was rewarded for the innovative approach of the new systems that became part of ‘Groundhog Beta’ but sometimes significantly differed from the Alpha version. Once again the team achieved 2nd place in the overall competition but also receiving the Innovation award. The success of the adapted machine proved that
the concepts within ‘Groundhog Beta’ are meaningful in terms of challenging the status-quo of tunneling technology. On the other hand, it became clear that it is now time to improve the reliability and to optimize the MTBM and support. This is why the team then invested all their efforts into optimizing what they had
36 | Summer 2024
Vegas, where the team has faced a desert-like soil with the first MTBM, ‘Groundhog Alpha’, the ‘Groundhog Beta’ machine had its Erosion System adapted for the more cohesive, sticky clay conditions in Bastrop. As the Erosion System of the machine must process the underground material while digging, its actions take place at the front, within, and outside of the machine. At the front, a cutterhead with a crushing mechanizm as well as a mixing element behind is placed, so that also medium- sized rocks can be divided into smaller ones. Since most of the soil in Bastrop consists of clay, the Erosion System also prepares the ground ahead of the cutterhead by conditioning it with a special foam mixture, which frees the processed soil from its cohesive consistency. As soon as the material is decomposed, it then gets transported through and out of the machine by using a suctioning mechanizm. Outside of the machine, an external sedimentation system ensures the constant circulation of the involved water – enabling a recycling process by separating the reusable water from the eroded material. Steering: This component enables the machine to dig
at angles, in different directions, and to handle vibrations resulting from the machine itself. This part involves a lot of sensors to enable autonomous machine movement. Lining: The next subsystem is in the middle part of
the machine and is the Liner System. It represents one of the most innovative parts the project to achieve efficient tunneling. The Liner system prints the tunnel wall while moving forward without interruptions. A pneumatic system transports polypropylene (PP) granulate into the Liner System. The PP granulate gets melted by heating elements, and the melted polymer is extruded, flowing to the outside of the machine where it cools to form the lining. Thus, the intended structure with strength to withhold the machine’s forces and pressure under the surface are achieved on the round surface of the machine. The result is a 15mm-thick tunnel wall liner that continuously gets extended as the ‘Groundhog Beta’ MTBM advances through the soil. Further, the tunnel wall could also be removed later, so that its material can be reused for the same or other purposes.
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