寒区不同材质垂直埋管测温方式差异性分析

寒区土壤温度场观测多采用垂直埋管方式，常用管材有铁管、PVC管、PPR管、PE管等，在实践中发现同一地点不同材质测管所测温度场存在较大差异.为研究几种常用测温管材测试值的差异性，2014年11月3日至2015年4月29日对四种材质垂直埋管与土壤直埋传感器的测温方式进行了现场比对试验.结果表明：（1）不同材质垂直埋管因其物理性质的差异，在测温过程中对温度场有不同程度的影响，PVC管和PPR管的测温值分别偏高于相应土层温度约0.8℃和0.3℃，而铁管和PE管则分别偏低于相应土层温度约0.4℃和0.6℃.（2）管材中温度场数据与土壤温度场数据相关性由高到低排序为：铁管 > PPR管 > PVC管 > PE管.（3）通过最小二乘法，求得铁管-土壤各层埋深温度场的转换系数，并得到铁管-土壤温度场拟合方程，经证实相关性显著.

Divergence analysis of the temperatures measured in different material vertical buried pipes in cold regions

Vertically buried pipes are often used to measure temperature field of frozen soil. In this study, iron pipe, PVC pipe, PE pipe and PPR pipe, which are often used in temperature observation, are investigated. It is found that there is significantly different among the temperature fields measured in pipes of different materials. Comparative tests of temperature measurements by the sensors placed inside the four types of pipe and a measurement by the sensors directly inserted into the soil were conducted from November 3, 2014 to April 29, 2015. The measuring depths were 5, 20, 40, 80, 120 and 160 cm. The measured soil temperatures in the pipes and directly in the soil were compared. The comparative analysis showed that:(1) Owing to the difference in physical properties, different materials of the pipes have different influence on the measured temperature field; the measured temperature in PVC pipe and PPR pipe are slightly higher than the true soil temperature about 0.8℃and 0.3℃, respectively, but that in PE pipe and iron pipe are slightly lower than the true soil temperature about 0.4℃ and 0.6℃ respectively; (2) After analysis and comparison, the measured temperatures in iron pipe, PVC pipe, PPR pipe and PE pipe are correlated with the true soil temperature with the order:iron pipe > PPR pipe > PVC pipe > PE pipe; (3) Using the least square method, transfer coefficient from the measured temperatures in iron pipe to the true soil temperature of each layer can be obtained. Thus, a fitted equation can be established between the measured temperatures in iron pipe and the true soil temperature, which is verified having significant correlation.