A common application for steel beams is for tunnel arches. Tunnels are used in underground storage vaults, in mining and in pedestrian pathways and vehicular roadways.
One of the largest underground storage vaults ever constructed is the site for burying nuclear waste at Yucca Mountain, Nevada. Curved steel beams support the main tunnel of the Exploratory Studies Facility which is 5 miles long and 25 feet wide. As the tunnel was being constructed, the ground conditions dictated the use of steel tunnel shoring: at times the ground was self-supporting and at other times the steel tunnel supports were required.
The Yucca Mountain Nuclear Waste Repository was to be a deep geological repository storage facility for spent nuclear reactor fuel, but it was defunded under the Obama administration.
Projects like the Deep Tunnel in Chicago which stores excessive storm-water run-off also use steel tunnel shoring.
Tunnel shoring is used extensively in mining. Steel beams are formed into a variety of shapes: full circles, 180 degree segments, 180 degree segments with straight tangents (a horse-shoe tunnel support), and variations on the above. Typically tunnel supports are supplied with mounting plates with bolt holes. Within the mine, circular steel chutes called “liner cans” are sometimes used to transport ore. Again, structural steel supports these cans.
Steel shoring is often required when constructing vertical shafts for mines. In this case the beams are installed horizontally to contain the pressure of the side walls of the shaft.
Pedestrian and vehicular traffic often requires tunnels to go under or through various barriers. In Chicago, for example, a pathway with tunnel supports allows pedestrians to walk along the Chicago River and then under Michigan and Columbus Avenue Bridges eastward to Lake Michigan.
For all of these applications steel supports often offer the best solution for tunnel shoring.