ABSTRACT
The geological and geotechnical context of the rocky massif of “La Maddalena Reconnaissance Gallery” and the results of excavation with an “open type” TBM are presented, with particular reference to the stretch between ch. 3+045 and 7+020 with overburden constantly over 1000 m, up to a maximum of 2000 m. Based on the registered data of the machine and the geomechanical characteristics of the rock mass collected during the tunnel boring, the real TBM excavation progress, total and net, and the advance values predicted by some empirical models, commonly used to forecast the TBM performance on the basis of the traditional rock mass classification indexes, are compared. The consequent critical analysis of the applicability of the empirical approaches to the excavation performance parameters prediction within the Ambin Massif represents an interesting base of knowledge, which is made available for the design of future excavations in similar geomechanical contexts.
