Tunnel boring is the civil engineering method of excavating a tunnel using a tunnel boring machine, a large rotating cutterhead that grinds through rock or soil while the machine advances along the bore, typically also installing a ring of precast concrete or steel lining segments behind it to support the excavated tunnel wall as it progresses. Compared with drilling and blasting, tunnel boring produces a smoother bore with less disturbance to the surrounding ground and surface structures, which made it the preferred method for major infrastructure projects such as the Channel Tunnel between England and France, completed in 1994, and numerous urban subway systems worldwide.
Facts
Core PrincipleTunnel boring works by driving a large rotating cutterhead machine through rock or soil in a continuous advance, excavating a circular tunnel without the drilling and blasting a hand-mined tunnel needs. 1 FAQs
Why are different tunnel boring machines used in hard rock and soft ground?
The ground sets the design: disc cutters for hard rock, soil pressure or support fluid to hold the face in soft ground.
The ground decides how the tunnel face is held. Hard-rock machines, which are gripper or double-shield types, operate dry and use disc cutters. In soft or mixed ground, earth-pressure balance machines and mixshields stabilize the tunnel face with soil pressure, and slurry shields rely on support fluids and separation plants. The choice depends on grain-size distribution, strength, groundwater conditions and the required lining technology.
Connections
Associated With
Field-to-technology association verified live; FROM end owned by fields section
Sources
1. Tunnel Boring Machine (Wikipedia)
Wikipedia contributors, Wikimedia FoundationLead section
A tunnel boring machine (TBM), also known as a "mole", is a machine used to excavate tunnels.
History, 1800s section
Maus had it built in 1846 in an arms factory near Turin, Italy.
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