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Topics Tagged ‘Soft Ground Tunneling’

Soft Ground Tunneling

Added on: September 27th, 2013 by Afsal Meerankutty 1 Comment

In Soft Ground Tunneling workers dig soft-ground tunnels through clay, silt, sand, gravel or mud. In this type of tunnel, stand-up time — how long the ground will safely stand by itself at the point of excavation — is of paramount importance. Because stand-up time is generally short when tunneling through soft ground, cave-ins are a constant threat. To prevent this from happening, engineers use a special piece of equipment called a shield. A shield is an iron or steel cylinder literally pushed into the soft soil. It carves a perfectly round hole and supports the surrounding earth while workers remove debris and install a permanent lining made of cast iron or precast concrete. When the workers complete a section, jacks push the shield forward and they repeat the process.