Tunnel boring machine
Tunnel boring machines are digging machines designed to bore tunnels, remove the waste, and coat the tunnel with a strong structure, to prevent the tunnel's collapse.
The cutting face is coated with superhard rollers. There are mechanisms that force the rotating cutting face into the uncut surface of the soil or rock. When the rollers encounter a rock, that pressure eventually causes the rock to fracture. The cutting face has holes in it that the pressure pushes the rock fragments through, where it falls on a conveyor belt, to be removed from the tunnel.
Some tunnel boring machines are built to bore through rock. Others are built to bore through looser material. When boring through looser material, or in porous rock, under the water table, the cutting head has to be sealed from the rest of the tunnel, so the tunnel face can be pressurized with a Bentonite slurry.
Some modern tunnel boring machines are designed so that, when they encounter a change in ground conditions, the cutting face can be swapped out for another, more suited for those ground conditions.
As of 2025[update] the diameter of the World's widest tunnel boring machine, known as Shanhe, in Jinan, China, is 17.6 metres (58 ft).[1][2]
References[edit]
- ↑ Sun Yu (2024-12-20). "世界最大直径水下盾构隧道掘进破千米" [The world's largest diameter underwater shield tunnel has been excavated for more than 1,000 meters]. 中国科技网 (Science and Technology Daily) (in 中文). Retrieved 2025-03-04.
- ↑
"Mega project in China: 17.5-meter TBM "Shanhe" is ready for construction site". Herrenknecht AG. Retrieved 2025-03-04.
Herrenknecht has built a Mixshield tunnel boring machine (TBM) for the construction of a two-storey road tunnel with three lanes in both directions in the eastern Chinese city of Jinan. The Mixshield technology is designed for the extreme conditions of the upcoming undercrossing of the Yellow River.