PROGNÓZOVÁNÍ VÝKONU STROJŮ TBM PŘI RAŽBÁCH VE SKALNÍCH HORNINÁCH S PÁSMY OSLABENÍ POMOCÍ TBM BEZ ŠTÍTU NEBO TBM S DVOJITÝM ŠTÍTEM TBM PROGNOSES FOR HARD ROCK WITH WEAKNESS ZONES, USING OPEN-GRIPPER OR DOUBLE-SHIELD SOLUTIONS

A wide-reaching review of TBM tunneling with open-gripper TBM, as opposed to double-shield TBM, where description of ground is less accurate, forms the basis of a prognosis method called QTBM. Some lessons from the numerous reviewed cases will be given, followed by a brief introduction to the classification-based empirical method. The TBM performance data base numbers some 145 cases or about 1000 km of TBM tunneling, whose overall performance is synthesized. Since the development of this method the data base has been increased to include double-shield TBM driving in hard igneous rock, also of similar abrasiveness to the case to be described in this paper: namely two tunnels in hard rock with weakness zones, to be tackled either by open-gripper or double-shield TBM. The planned tunnels will form a high-speed Norwegian rail link to Oslo from Ski in the south, to be driven either by drill-and-blast from several fronts, or using TBM for 7.9 km and 9.6 km long tunnels. Water ingress must be limited in various localities due to settlement risks. Data collection was mostly by Q-histogram classification of more than 300 rock cuttings, while some drilling and seismic refraction profiling was utilized in the case of weakness zones.