Tunnel plug
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Hickey can often see abnormalities in the chart where a tunnel is located, sometimes with startling precision. Once all of the measured waves are recorded, Hickey charts them on a computer through a process called seismic refraction tomography. “A tunnel affects the density and the elasticity of the ground around it,” he says. The wave may quickly refract, for instance, back up to the receiver. If a tunnel is underneath where Hickey and his team are working, they can usually note that the wave will travel in an unusual kind of way. “We’re looking at the velocity and path of each.” The technique, he says, is similar to ultrasonic imaging that is used in hospitals to make a medical diagnosis. “We’re measuring the timing and propagation of the waves,” says Hickey. Then, he uses a receiver hooked to a seismograph to track the resulting seismic waves as they travel through the ground. Basically, he bangs a hammer onto a line of sensors called geophones, which are placed strategically aboveground. Craig Hickey, a professor of geological engineering and physics at UMiss, directs the project. The tunnel detection work is led by the University of Mississippi and the University of Alberta in Canada. and foreign universities that are partnering on homeland security research.
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They could allow just enough time for people to evacuate.īoth projects are part of a series of research grants issued recently by the S&T Directorate’s International Programs. These air bags would be made of some kind of heavy-duty, but inflatable, material that would temporarily seal breaks in the tunnel. They’re trying to design a system that can automatically deploy giant air bags if a tunnel starts to collapse or sustains a gaping blast hole. Other researchers are examining the structure of large tunnels, such as railroad and highway tunnels that are crucial to everyday life. border, usually by smugglers and possibly by terrorists. By analyzing the movement of these waves (sometimes called rays), experts may be able to detect the presence of tunnels that are dug illegally along the U.S. With funding from the DHS Science and Technology Directorate (S&T), researchers are tracking how seismic waves caused by vibrations travel through various layers of soil. In short, they’re trying to detect tunnels that shouldn’t be there … and protect the ones that should. Scientists and engineers from different countries are peering and roaming about underground-that’s, literally, underground-to examine tunnels. (December 2007) There’s a whole underground culture working for Department of Homeland Security (DHS).