利用红外热像测定土遗址导热系数的方法研究

土遗址土体加固效果的无损测试技术是目前土遗址保护加固之中急需解决的一个重要问题。为此探讨利用红外热像技术进行土遗址加固保护的无损测试,设计了相应的试验装置,并利用新疆交河故城遗址现场取得扰动土制成不同物理条件下的模型进行导热系数测定试验。分析土样表面温度随时间的变化规律,并根据非稳态导热理论反算出土样的导热系数。为了验证红外热像这种非接触无损测定土体导热系数方法的可靠性,在同样的土样上利用热特性分析仪(KD2 Pro)直接测量了土样的导热系数,两者结果差值甚小,证明了红外热像技术测定土体导热系数的可行性。还研究了干密度、含水率对遗址土体导热系数的影响作用。结果表明,在含水率一定情况下,遗址土体导热系数随干密度的增加而增大;在干密度一定情况下,遗址土体导热系数随含水率的增大而增大。研究结果可为土遗址土体加固效果评价作参考。

Experimental study on coefficient of thermal conductivity of earthen ruins by using infrared imaging technique

With the aim of reinforcing the soil in earthen ruins, anondestructiveinfrared imaging technique for studying soil conditions was explored. Thedisturbed soil samples of various physical conditions collected from the Jiaohe Ruins site were tested to determine the coefficient of thermal conductivity. Through analysis ofthe relationship between soil surface temperature and time,using unsteady state heat conduction theory, the coefficient of thermal conductivity of the soil was calculated. To verify reliability of this method, which measures coefficient of thermal conductivity of soil by an infrared imaging technique, the coefficient of thermal conductivity of the same soil was measured using thermal analyzer KD2 Pro.The difference between two test methods is small. This demonstrates the feasibility of measuring the coefficient of thermal conductivity of soil usingthe infrared imaging technique. The effect of different dry densities and moisture on the coefficient of thermal conductivity of the soil was studied. The results showed that if the dry density is increased, the coefficient of thermal conductivity of soil with constant water content is increased, too; if the water content is increased, coefficient of thermal conductivity of soil with a constant dry density is increased too.