隧道衬砌渗漏水红外辐射特征影响因素试验研究

EXPERIMENTAL STUDY OF FACTORS AFFECTING THERMAL INFRARED RADIATION CHARACTERISTICS OF TUNNEL LINING WATER LEAKAGE

针对隧道渗漏水红外热成像检测问题,总结渗漏水红外辐射特征的影响因素(渗漏温差、流量、位置以及衬砌表面材料等),采用室内混凝土试块注水模拟各工况下隧道衬砌渗漏水,并利用红外热像仪记录分析渗漏水的红外辐射特征,研究不同因素对渗漏水红外辐射特征的影响规律。试验结果表明:渗漏水热图像呈现水流方向温度递减,水流横断面温度呈抛物线分布的规律;随渗漏水温差增大、渗漏水流量增大、渗漏面与水平面夹角减小、渗漏表面辐射率减小,渗漏点温度值基本呈线性增加,沿渗漏点水流方向温度梯度增大,但沿渗漏点水流横断面温度梯度减小。另外,针对不同衬砌表面材料,建立隧道衬砌表面辐射率修正指标,并且编写Matlab图像处理程序提取渗漏水红外热图像特征。结果显示:经过辐射率修正后的渗漏水形状和面积与实际更符合。研究成果可为红外热成像技术在隧道衬砌渗漏水的快速检测与分析提供依据与方法。

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.