GEOMECHANICAL CHARACTERIZATION OF ROCK MASSES FOR TUNNEL EXCAVATION WITH TBM

The prediction of Tunnel Boring Machine (TBM) performances and the comprehension of the relationship between the geological, mechanical and structural features of a rock mass and the machine behaviour are fundamental in order to select the most effective tunnel construction methods and to estimate the condition of excavation in terms of time and economic costs of the infrastructure. The general purpose of this work is to carry out predictive models utilisable during the early stage of tunnel planning and realisation; for this purpose, many approaches have been considered. Simple and multiple, both linear and nonlinear, regression analyses have been performed in order to achieve an empirical equation able to estimate the principal TBM performance indices (ROP and FPI). In addition, Multiple Correspondence Analysis and clustering have been developed. A modified version of the Rock Engineering System has been performed and used to obtain a predictive model. This study focuses on the exploratory tunnel named “La Maddalena”, located in Northern Italy, Western Alps, where geological surveys data have been continuously performed during tunnel construction; this allowed the collection of a large amount of geological, geotechnical and TBM performance data.