Abstract
Thus far, there has never been any cases where infrared thermography (passive method) was applied to detect flaking near the surface of the concrete in subway tunnels, which are not affected by sunlight. Through this research, a method was developed, which can actually be put into practice to detect flaking of the decking concrete used in subway tunnels using infrared thermography. At first the temperature conditions (and other elements) that would allow detection of flaking in a box-type tunnel and in a shield tunnel, both in use, were analyzed.
Then, detection of flaking inside a box-type tunnel was carried out, and a method to identify the day that was appropriate for infrared thermography measurement was developed based on the temperature outside, having considered accuracy of infrared thermography measurements and the relationship between temperature outside and temperature in the tunnel.
Furthermore, on the same section meticulous concrete surface hammering tests were carried out besides the infrared thermography measurement, and the effectiveness of this method was verified having compared those results with results of special general inspection based on the maintenance standards for railway structures.
