The paper presents the results of the research in the field of mechanical rock cutting by disc cutters of the tunnel boring machines. Investigation of rock cutting mechanism was focused on the interaction of the system cutter-rock with a view to identify the dominant characteristics and parameters of this system. The theoretical aspects of rock cutting by disc cutters were verified using the comparison of the monitored data from tunnels with data from conventional engineering-geological survey. Apart from analytical and statistical methods, also the means of artificial intelligence were applied, which enabled to investigate the mutual relations between parameters of the excavation process determined by application of various methods. Acquired results enabled to complement and specify the results of conventional geological, engineering-geological hydrogeological and geotechnical survey. The paper also delivers a novel solution to the problem of optimization of the energy consumption of the TBM.

1 Introduction

The research of mechanical rock cutting has been the main objective of the research group at the Institute of Geotechnics, Slovak Academy of Sciences (IGT SAS). After the first stage of research performed in laboratory conditions using the experimental laboratory drilling rig, the investigation moved to the in-situ conditions of the underground constructions. Several series of monitoring and optimizing systems of the tunnel boring machines (TBM) performance were developed at the IGT, installed at various TBMs, such as WIRTH TB-II-330H/M deployed in excavation of the exploratory gallery of Branisko motorway tunnel, and Voest-Alpine ATB 35HA driving the exploratory gallery of the Višnové motorway tunnel.

The monitoring systems provided data acquisition of TBM parameters, scanned in 2-seconds intervals, which were filtered and used for subsequent calculation of relevant parameters for assessment of the tunnelling process, the values were then averaged for approximate 25 cm long tunnel sections. The sampling period of 2 seconds enabled to acquire the data with density corresponding to the continuous record depending on the TBM's advance rate. One single revolution of the TBM cutterhead produced 2–3 values of regime parameters. Such outputs were archived along with the information from engineering-geological prospecting, thus forming an extensive database for further analyses and theoretical investigation. Database processing involved conventional mathematical and statistical methods, as well as the alternative methods, such as means of artificial intelligence.

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