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Abstract The concrete specimen coated with fireproof paints is used to simulate tunnel lining under different conditions. The mobile equipment based on line-array charge-coupled device(CCD) is designed and corresponding softwares are developed to make the model test on automatic detection of cracks in tunnel lining. Gray distribution of image and accuracy of crack detection are selected as two quantitative indices for assessing automatic detection performance. The influencing law of factors such as detection distance，light source illuminance，effective pixel and detection speed affecting automatic detection performance is summarized. The model test results are as follows：The gray distribution of image along crack width direction shows wave valley features. Detection distance and effective pixel have little influence on the gray distribution of image，but mainly affect the accuracy of crack detection. With the decreasing detection distance and increasing effective pixel，the accuracy of crack detection increases linearly. Light source illuminance and detection speed have great influence on both the gray distribution of image and the accuracy of crack detection. Too high or low light source illuminance can cause a reduction of the accuracy of crack detection. With the increasing detection speed，the accuracy of crack detection decreases linearly.
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Received: 06 April 2012
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2012, Vol. 31 
