Sofia Metro Line 3 tunnel (completed tunnel view)


The 3rd Metro Line Project in the city of Sofia is aimed to ease the traffic on some of the most congested boulevards linking the city's south-western neighbourhoods with its eastern districts. The entire line is 16 km long and includes 8 overground and 11 underground stations. Line 3 will interchange with the existing lines 1 and 2, and will underpass below sensitive buildings like the Law Office Rusinova & Rasheva's, as well as undercrossing the Perlovska river. Main tunnel consist in a single tube configuration excavated using an EPB TBM of 9.4 m of boring diameter.

Tunnelconsult has been in charge of the detailed design of geometrical and structural segmental lining, TBM definition and follow-up until commissioning, ground treatments, monitoring, TBM entrance and exit, EPB pressure and temporary works. During construction works, Tunnelconsult also monitored the TBM performance and designed a solution for building an intermediate connection shaft minimizing the works inside the main tunnel, to not interfere with the TBM operations and be able to advance most of the works regardless the TBM position.

Ground & Building monitoring sensor devices layout


Hanoi Pilot Light Metro Line, section Nhon – Hanoi Railway Station, is a very important project aimed to ease traffic congestion and reduce emissions in Hanoi City. The first phase of this line starts from Nhon to Hanoi Railway Station, with 8.5 km of elevated stretch and 4.0 km underground, from which a 2.57 km is a twin-bored tunnel excavated by an EPB TBM of 6.3 m of excavation diameter.

Tunnelconsult provide its know-how to make the detailed design of the tunnel segmental lining, connection galleries & ventilation shaft and its necessary ground treatments, manage and follow-up the Geotechnical Baseline Report & additional campaign, as well as to make the Building Risk Assessment and set the Monitoring Plan both for civil works and existing buildings.

Top view sacrificial rings in station


The Chennai Metro Rail Project included the design and construction of two corridors, Corridor 1 (Washermanpet – Airport) and Corridor 2 (Chennai Central – St. Thomas Mount. Underground works have been divided into 5 packages. Packages UAA-02, UAA-03 & UAA-04 consist in 3.6 km, 2.9 km and 3.4 km respectively long twin-tunnels that are bored mainly in younger alluvium of sandy and clayey soil. Bedrock was encountered in some stretches of the tunnel alignment, consisting in both Archaean charnockite and sedimentry formations, mainly shale and sandstone. Three Earth Pressure Balance (EPB) TBM have been used for the excavation of the tunnels, with a segmental lining consisting of 5.8 m of internal diameter and rings formed by 275 mm thick segments.

Tunnelconsult provided Technical Assistance for design and construction to the Contractor in Corridor 1 (UAA-02 & UAA-03 packages) and Corridor 2 (UAA-04), analysing the geological conditions along the alignment and assessing for EPB pressures definition, TBM break-in & break-out procedures at stations, recommendations regarding TBM cutting tools, site equipment foundation designs, design of fiber reinforced sacrificial rings for station crossing, guidelines for ground treatment for cross passages and recommendations on mixed face conditions excavation.

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