From Factory Acceptance Tests (FATs) to launches
and breakthroughs, across the globe there are hundreds tunnel boring machines preparing for action or already have been in the midst of boring on projects of all kinds. T&T spotlights a brief few in what can only be a small sample of the many large TBMs at work or being prepared.
GROWING TALLY OF TERRATEC EPBMS UNDERWAY ON CHENNAI METRO
Terratec is supplying a package of five TBMs as part of tunnelling on part of the Chennai Metro project, in India.
Three of the earth pressure balance machines (EPBM) have begun excavation so far on the Lot TU01 package of Corridor 3, as part of the Phase 2 expansion works for Chennai’s metro. The city’s metro network is already the fourth longest in India with two lines over almost 55km.
Phase 2 adds three new Corridor branches (Corridors 3-5) totalling 118.9km in length to the network.
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By GlobalDataBeing built in twin tunnels between (north-to-south) Madhavaram and SIPCOT, Corridor 3 is 45.8km long and includes 48 stations in twin tunnels. The Lot TU01 package is at the northern end of the long line, near Madhavaram.
The first of Terratec’s 6.61m-diameter EPBMs was delivered in May 2022. Shortly after, the following two machines passed their factory acceptance tests (FAT) and were shipped. Tunnel boring began on site in October. Onsite assembly is underway in early 2023 for the fourth of the five EPBMs, supported by the Terratec field service team. The code numbers for the four machines are S96-99.
The fifth TBM (S81B) has passed its FAT. It was previously used on Pune metro’s Phase 1 16.5km-long Purple Line. The EPM worked on the 2.1km-long section between Swargate and Budhwar Peth stations.
The TBMs have versatile mixed-ground dome-style cutterheads. Expected geology mainly sand, silt and clay, with some weathered rock. The tunnel lining is concrete rings (5+1) of 275mm-thick segments.
Tata Projects Ltd is contractor on the lot and plans to use a total of seven TBMs for the tunnelling works, which run (north-to-south) between Venugopal Nagar and Kellys metro stations – a distance of 9km. Total tunnelling for TBMs in the lot equates to 18km.
The works also include construction of diaphragm walls and the machine launch and retrieval shafts at four stations.
RAPID SUCCESS ON A SOUTH AMERICA FIRST FOR CRCHI
In late 2022, China Railway Construction Heavy Industry Corporation‘s (CRCHI) first hard rock TBM in South America added to its milestone achievements by achieving an advance of more than 1000m in a month, boring on the San Gawang hydropower project, in Peru.
The high progress rate for the month came from increasingly higher single shift advance rates achieved for the 5.83m-diameter TBM through November, resulting in the milestone 1000m monthly rate to be exceeded – reaching 1007.9m – by 6 December.
Geology is medium to high strength rock with good stability, says CRCHI, which supported the TBM assembly and commissioning with its onsite service team.
Progress rates on shifts doubled from 10m to 20m and then higher during November, the company reports. CRCHI adds that the maximum progress rates achieved on a single shift was more than 26m. The maximum advance in a day was 46m.
The 209MW hydro project has Chinese investment as part of its Belt and Road Initiative, in South America. CRCHI says the San Gawang hydropower project is expected to greatly promote the optimal allocation of regional water resources in support of sustainable economic and social development in the region.
The project is the first power sector investment in Peru by Chinese enterprises, says CRCHI
ROBBINS TBM STARTS ON NEPAL’S SUNKOSHI MARIN PROJECT
A 6.4m-diameter Robbins double-shield TBM was launched late 2022 on the Sunkoshi Marin Diversion Multipurpose Project (SMDMP), in Nepal.
The TBM is boring on the major hydropower tunnel for the project – the 13.1km-long headrace.
Contractor on SMDMP tunnelling project is China Overseas Engineering Co, which was awarded the job in early 2021.
The launch of the TBM marked the start of construction on the headrace tunnel. It is to convey water from the Sunkoshi River via a concrete diversion weir structure, and desander to remove silt, before the tunnel takes the flow to a new surface powerhouse on the Marin River.
SMDMP has been declared a National Pride project by the Nepalese Government. It is to combine hydropower as well as irrigation benefit, as the water will flow to fields in the districts of Dhanusha, Mahottari, Sarlahi, Rauthat and Bara in the Terai Plains
MILESTONE PROGRESS FOR LONATO TBM ON MEDITERRANEAN TEN-T
The single TBM boring the 4.75km-long, twin tube Lonato Tunnel in north Italy has completed the first of the 8.8m i.d. concrete-lined rail tunnels and is about to get underway on constructing the second.
With geology of glacial moraine including large boulders, the JV contractor chose a 10.03m-diameter earth pressure balance (EPB) machine, manufactured by China Railway Engineering Equipment Group (CREG). The EPBM has a double screw, boulder trap and is designed for high groundwater pressure. It operates on single screw conveyor mode or double mode depending on the ground conditions and water pressure.
Lonato Tunnel is on a strategic Mediterranean rail corridor in the TEN-T high-speed network being developed across the continent with EU-backing.
The tunnel is on Lot 2 of the Brescia East to Verona portion of the Milan to Verona route being developed by Italian network rail owner and operator Rete Ferroviaria Italiana. Lonato Tunnel has a total length of almost 8km, dominated by the twin TBM-bored tunnels.
The contractor is Cepav Due, a joint venture of Saipem, Pizzarotti, and ICM. Tunnelling subcontractor is Seli Overseas (part of Webuild)
The CREG TBM was shipped from China to north Italy and was launched in late 2020.
Breakthrough to complete the first of the twin tunnels was achieved in September 2022. The EPBM was then dismantled, moved and reassembled, and tunnelling work is getting underway for the parallel tube.
When covid was beginning to take hold, the early preparations for Lonato Tunnel project were in progress. Work continued as with many major infrastructure projects around the world that are important for national benefits, especially important transport projects with major tunnels.
