BUILDING BIG Tunnel Basics
Tunnel Basics
Tuesdays in October on PBS (check local listings) _  
Forces that act on Soft-Ground Tunnels.

Soft-Ground Tunnel: Forces
The heavy, wet ground pushes on all sides of the tunnel. The tunnel's walls are squeezed by the ground.


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_There's even more to explore at the BUILDING BIG web site, check it out at www.pbs.org/buildingbig.



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