Penetration tests for TBMs and their practical application

Characterizing performance of tunnel boring machines (TBM) is important for numerous contractual and technical reasons. A common tool to determine machine performance in the field is the penetration test. The purpose of the penetration test is to operate the TBM for a defined period of time under normalized conditions that allow for interpretation and comparison between tests. The result of a penetration test is a thrust-penetration curve that reflects the excavatability of the rock mass. Prediction models use thrust-penetration curves to calculate the expected performance of a TBM in specific ground conditions. This paper provides a review of recent practice including testing at the Norwegian University of Science and Technology (NTNU) along with research by Villeneuve and Käsling. Each of these methods includes excavation at certain thrust levels and rotational speeds for a certain distance. These existing methods have a number of disadvantages that lead to fairly slow tests, which the proposed methodology aims to eliminate. © 2012 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.