Author-created version.
This paper is published on Rock Mechanics & Rock Engineering, Springer Vienna (DOI 10.1007/s00603-014-0554-4). The final publication is available at http://link.springer.com/article/10.1007/s00603-014-0554-4.
Il paper รจ stato pubblicato sulla rivista Strade e Autostrade n. 5 (2014), EDI-CEM Srl, http://online.stradeeautostrade.it/.