Abstract

Tunnel boring machine (TBM) operational data can be seen as a function of three main influences: the machinery of the TBM itself, the way the TBM is operated, and the excavated rockmass. Whereas the processing of TBM data must be done by computer-aided methods, the interpretation is typically done visually and is highly dependent on the user’s prior experience. One way is to inspect the raw data itself, and another is to inspect computed parameters (specific penetration, specific energy or torque ratio). Either way, the goal is to find distinctive patterns that indicate changes in the rock mass conditions, and therefore it is crucial to find parameters that bear as much information as possible. The goal of this paper is to introduce the new parameter "theoretical advance force" (FN,theo) that was developed in the course of systematic analysis of TBM operational data from the exploratory tunnel Ahrental Pfons (part of the Brenner Base tunnel project). FN,theo is back-calculated from the measured cutterhead torque and the measured penetration. The theoretical advance force shows very promising results with the data at hand, yielding more pronounced and well-defined patterns that correlate better with the encountered rockmass conditions than several other common parameters.

Introduction

The Brenner Base Tunnel (BBT) is a railway tunnel that is currently under construction and connects the cities of Innsbruck (Austria) and Fortezza (Italy). With 120 km of main tubes – railway tunnels, a 61 km long exploratory tunnel and 49 km of other tunnels (e.g., crosscuts) the tunnel system is considered to be the longest in the world today [1]. A part of BBT’s exploratory tunnel on the Austrian section is driven by an open gripper tunnel boring machine (TBM, figure 1) and will be used for logistics and maintenance after the construction. It also offers a geological forecast for the excavation of the main tunnel tubes [2]. To achieve this goal, the data collected from the 16.7-km long exploratory tunnel Ahrental-Pfons is thoroughly analyzed [3]. Innsbrucker Quarzphyllite; and lower and upper Schieferhülle are the main lithological units encountered in the excavation [4].

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