Semester

Spring

Date of Graduation

2011

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

Kenneth Means

Abstract

Inflatable technology has become a popular alternative for replacing conventional ways of building structures. Inflatable structures offer the benefits of being lightweight and portable while maintaining needed rigidity and reducing production costs. These benefits have prompted the use of inflatables in confined spaces such as pipes and tunnels to act as barriers with minimal infrastructure modification. This work focuses on using these inflatables, or plugs, in transportation subway tunnels as a way to mitigate threats such as floods.;In order to stop the flow of water, the plug must be capable of being pressurized and apply enough pressure on the tunnel walls so that it does not move while being acted upon by an opposing force. A small scale test bed was constructed in which a plug could be inflated inside of a pipe representing a tunnel with one closed end. This closed space between the closed tunnel end and the plug could then be pressurized with water applying an opposing force on the plug trying to push it out of the tunnel. The plug was set at different pressures while the tunnel pressure was raised to the plug pressure until slippage of the plug occurred. This pressure differential between the plug and tunnel was recorded and used to calculate a friction coefficient. Friction coefficients were calculated for three different materials lining the tunnel so a comparison could be made. These friction coefficients were also compared to laboratory friction machine testing of the same lining materials. This comparison showed that the tunnel and plug friction coefficients were much lower than the laboratory friction machine tests.;Rates of water leakage around the plug were also studied. The leakage rates were recorded for several different plug pressures while varying the tunnel pressure accordingly. It was observed that as pressure differential decreased between the plug and tunnel, the leakage rate increased. The leakage rates were also compared to the friction tests and indicated that an increased leakage rate caused a decrease in the friction coefficient. Leakage rates were also scaled and estimated for a larger plug and tunnel diameter.

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