Tunnels are built in a variety of materials, including soft mud and heavy rock. The design of tunnels depends on factors such as: Terrain conditions, Ground water circumstances, The diameter and length of the tunnel drive, The size of the tunnel, The material support for tunnel drilling  Here are some types of tunnels: Cut-and-cover tunnels: These tunnels are constructed in a shallow trench and then covered over. Box-shaped cut-and-cover tunnels are common for transportation tunnels. Bored tunnels: These tunnels are constructed in situ, without removing the ground above. Tunnel Boring... Show more

Tunnels are built in a variety of materials, including soft mud and heavy rock. The design of tunnels depends on factors such as:
Terrain conditions, Ground water circumstances, The diameter and length of the tunnel drive, The size of the tunnel, The material support for tunnel drilling 

Here are some types of tunnels:
Cut-and-cover tunnels: These tunnels are constructed in a shallow trench and then covered over. Box-shaped cut-and-cover tunnels are common for transportation tunnels.
Bored tunnels: These tunnels are constructed in situ, without removing the ground above. Tunnel Boring Machines (TBM's) are used for mechanized tunnel excavation.
Immersed tunnels: These tunnels are created by sinking a tube into a body of water.
Water tunnels: These tunnels are below-ground channels used to transport water to areas with large populations or agriculture. They are frequently part of aqueducts.
Circular tunnels; These tunnels are strong and resistant to external pressure caused by water, soil, and ground. They are mainly used for sewage lines and are not suitable for railways and highway transportation.

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