Tunneling Through Soft Ground

Boston's Big Dig was perhaps the most complex and expensive tunneling project in human history. You may take for granted the nicely paved roadway that takes you under downtown, and perhaps you will even complain about the seemingly bizarre twists and turns that the tunnel takes. What you may not know is that building this tunnel system involved some very difficult challenges. These included the loose fill and clay that underlays the ground surface, the existing maze of tunnels, conduits, sewers, etc., and the fact that there was an existing elevated highway above the tunnel, along which all traffic had to continue for the 10+ years that this project was under construction.

In this engineering project, you will examine a few of these challenges, using sand to represent the soft ground through which tunnels in Boston must be dug.

Your task:

You have been contracted to build a tunnel that is at least 30 cm, an opening no larger than 3 cm, and that includes at least one significant turn. The tunnel must be, at its deepest point, at least 10 cm below the ground surface, measured from the top of the tunnel.

You may use (but are not required to use), as part of your tunnel construction, the following materials: a limited number of popsicle sticks and file cards.

The following tools will be provided to you: glue guns, glue sticks, scissors, tape, small saws.

You will be given sand in a container, along with water to keep the sand damp as needed.

Background information on Tunnels