Colle Baccotto Tunnel – Brescia Verona High Speed Railway (Italy)

Italy
CLIENT:
Cepav Consortium
Work activities:
Final and construction design, consulting services during construction.
Place:
Italy
OVERALL SYSTEM LENGTH:
2 Km
Period:
2019 -2025
 

Overview

Colle Baccotto Tunnel is a very complex shallow tunnel, located along the Brescia Verona High Speed Railway next to Peschiera del Garda (VR), currently under construction. The project involves excavation of a short tunnel (240 m) part of a challenging system of cut and cover tunnels and deep trenches reaching an overall length of about 2 km. Tunnel cross section is suitable for a double track line with speeds between 250 km/h and 300 km/h.

The executive design and construction stage of the whole system of tunnels and trenches was carried out by Alpina Spa since 2018. The railway alignment is parallel to the existing A4 highway road and passes under the SP 28 road which overpasses the A4 along a bridge, close to the East tunnel portal.

The tunnel is excavated for its whole length using a full face mechanical excavation in the chaotic moraine of Garda lake, under the water table. To carry out excavation, drainage ahead of the tunnel face was necessary as well as at the invert by means of a wellpoint system. Stabilization and consolidation measures consists of 600 mm single-fluid jet grouting columnar treatments along the crown, sidewall and within the face of the tunnel. Primary support is composed by steel ribs covered by lining of shotcrete reinforced with steel fibres. Final lining consists of a cast in situ revetment with a thickness variable in the range 80-120 cm.

Design and construction of the East Portal required a peculiar reinforcement structure of the existing SP-28 abutment to avoid excessive settlements during tunnel excavation. To reduce the the aquifer before starting tunnel excavation inside the reinforcement structure, a system of deep drainage wells was designed and drilled which allowed the excavation to begin safely under the existing abutment. A continuous monitoring system was foreseen to control the bridge structures and the highway road conditions during the entire work.

Capitale Sociale € 1.155.170 interamente versato
C. F. e iscrizione al Registro Imprese di Milano 01033390392
REA 1337939
Partita IVA 10241540151

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