ABSTRACT
The Brenner Base Tunnel is a railway tunnel currently under construction which is part of the Scandinavian-Mediterranean corridor (SCAN-MED) that will connect Fortezza in Italy to Innsbruck in Austria, running under the Brenner Pass.
At the southern end, the Brenner Base Tunnel runs through the Isarco Valley between Mules and Fortezza. Here, in addition to the Isarco River, the tunnels must also pass underneath two important roads: the SS12 state road and the A22 (Modena-Brenner) motorway.
From a geological-geotechnical point of view, this sector of the valley is characterised by extremely variable soil conditions, ranging from bedrock to debris flow and alluvial deposits below the water table.
This article presents the soil subsidence analyses and control monitoring carried out during the full-bore excavation of the two line tunnels under the SS12 and the A22, after preventive consolidation measures. In particular, the paper describes the analyses of the data actually acquired with the automated surface monitoring system; using these data, it was possible to detect several variations from the design forecasts and to highlight the effects of the consolidation methodology used (Quick Set Jet-Grouting (QSJG®)) in the assessment of subsidence phenomena.
