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Abstract In light of infrared thermal imaging of tunnel leakage detection，the factors such as temperature and flow of water leakage，water leakage location，materials of lining surface and so on，affecting thermal infrared radiation of water leakage are summarized. The concrete specimen is used to simulate water leakage of tunnel lining. The infrared radiation characteristics are recorded and analyzed using infrared thermal imager；and the influencing law is studied. The experimental results are as follows：Thermal image presents temperature of water leakage decreasing along water flow direction，while temperature along water flow cross-section showing parabolic distribution. With the increasing water leakage flow and temperature difference，decreasing angle between horizontal surface and leakage surface，decreasing emissivity of leakage surface and temperature of leakage points increasing linearly，the temperature gradient along water flow direction increases linearly，but the temperature gradient along water flow cross-section decreases. In addition，as for the infrared radiation characteristics with different surface materials，the emissivity correction indicator is established；and the leakage characteristics of infrared thermal images are extracted with Matlab image processing program. The results show that the shape and size of water leakage after modified agree well with the actual one. The study results can provide basis and means for rapid detection and analysis in tunnel operation using infrared thermal imaging technology.
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Received: 17 June 2011
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2011, Vol. 30 
