On September 27th, China’s first EPBM to be exported to South America, manufactured by CRCHI, left the production line. With a total length of 105m and an excavation diameter of 9.8m, the TBM will be soon deployed on Lot 1 of the Santiago Metro Line 7 project in Chile – the first metro project in South America constructed by a Chinese company using TBM tunnelling.
The total length of Lot 1 of the Santiago Metro Line 7 project is approximately 7.9km, of which 6.7km will be excavated by TBM. The project under crosses the Mapocho River, to a length of 60m, with the riverbed just 10m above the tunnel crown. The tunnel mainly passes through fine-grained soil, silt, clay, sand, gravel, pumice formation, and volcanic rock formation (granodiorite). The minimum radius of the alignment is 250m, which requires a high turning capacity from the TBM.
Based on the alignment’s ground conditions, the R&D team at CRCHI has equipped the TBM with a host of independent key technologies. The cutterhead adopts a composite design of six spokes and six panels, with a central support. Disc cutters, drag bits, and gauge scrapers dress the cutterhead for the full-face excavation of the tunnel, with all detachable cutting tools replaceable from the back of the cutterhead. The cutterhead is also capable of bidirectional rotation for muck discharge. When the TBM needs to turn, the stroke difference of each group of propulsion cylinders is adjusted to meet the minimum turning demand of the alignment.
The Santiago Metro Line 7 has a total length of 26km and a construction period of six years, making it a key project for the Chilean government. The line traverses seven urban zones in the capital, with plans to build seven island style stations and construction shafts. After the completion of the project, the entire line will take just 43 minutes, which will shorten the commuting time between the two terminal stations by 54% and provide fast and convenient transportation services for over 1.36M residents.