Hard rock tunnel boring machines – State of the art 2020

At this year's International Planning Design and Construction (IPDC) Workshop of the Unit of Project and Construction Management (i3b) of the University of Innsbruck, a selected group of tunnelling engineers took a closer look at the state of the art of hard rock tunnel boring machines and the challenges of tunnelling systems along the Brenner axis. The three currently active construction contracts using mechanized tunnelling technology at the Brenner Base Tunnel have an intersection of comparable geological/geotechnical conditions (quartz phyllite, schist, gneiss and granite) and yet different machine types were selected: a Gripper TBM for the Tulfes-Pfons exploration tunnel – H33, three Double Shield machines for the Mauls 2/3 contract and four Single Shield machines for contract H51. The focus of this workshop was accordingly: from geology/geotechnics to the key specifications of the TBM as a basis, followed by the consideration of the type-independent TBM parameters, the differences as well as advantages and disadvantages of the three machine types and finally an outlook into the future regarding further developments and need for innovation. This article summarizes the contents of the workshop. © 2019, Ernst und Sohn. All rights reserved.