SUMMARY
Due to the usually strict construction schedules and considerable lengths of tunnel drives, TBM tunnelling represents state-of-the-art excavation method for long alpine tunnels. However, this kind of tunnel construction is always associated with a considerable amount of uncertainty, having two major impacts on the TBM advance: -Various adverse occurrences at the tunnel face, such as mixed face conditions orstructurally controlled face failure – “blocky rock mass”, imposing reductionsof the achievable performance. The reduction is caused either by the need toadvance with sub-optimal operation parameters (reduction of rpm, thrust, etcetera) and/or increased inspection and maintenance efforts. -Usage of additional and/or auxiliary measures in order to enable a safe TBMadvance in the first place (e.g. various injections, shield smearing, installationof pipe roof umbrellas et cetera). As the additional time required by encountering circumstances as described above can’t be anticipated, no realistic and fair construction time query can be made in the tender. The model presented in this publication uses a very simple solution for the aforementioned issues: the construction activity during TBM advance is divided into three categories: regular advance, hindered advance and event-driven-advance stop. Each scenario is assigned a different accounting modality for time dependent construction cost. The delimiting criteria defining the threshold between the regular advance and the hindered advance are based on systematic evaluation of TBM data, supporting visual inspections of the rock mass behaviour and allowing clear identification of possible face instabilities. Four different TBM tunnels have been evaluated in order to validate the relationships and thresholds presented in the scope of paper. Finally, emerging technology of photogrammetric face surveying on a hard – rock TBM is briefly discussed. Its potential for future development and additional insights on the TBM process data is presented.

Svensk titel: KORREKT ERSÄTTNING AV KOSTNADER VID TBM DRIFT – EN NY MODELL BASERAD PÅ TBM DATA