冷镜露点技术是一种快速测试非饱和土吸力的间接方法。本文简要介绍了冷镜露点仪的工作原理和试验方法,利用Decagon公司生产的WP4C冷镜露点仪测试非饱和成都黏土压实土样的总吸力,以Van Genuchten模型为基础,结合Origin软件对试验结果进行了曲线拟合,得到成都黏土的SWCC曲线,并给出拟合参数参考值。借助CT-3031型电导率仪测得土样的渗透吸力,由基质吸力等于总吸力减去渗透吸力,间接得到土样的基质吸力-含水率关系曲线。对比滤纸法测试相同土样得到的SWCC曲线,得出相同含水率时冷镜露点技术测得的吸力值低于滤纸法测得的值,和国外文献的相关结论一致,验证了冷镜露点技术测试吸力具有快捷、方便、准确等特点。指出冷镜露点技术在非饱和成都黏土吸力测试应用中是可行的,同时可推广到国内岩土工程相关领域的吸力测试中。 Cold mirror dew point technique is an indirect method to quickly test suction of unsaturated soil. This article briefly introduced the working principle and test method of the cold mirror dew point instrument. Using the WP4C cold mirror dew point instrument produced by Decagon Company to test the total suction of the unsaturated clay-compacted soil sample in Chengdu, based on the Van Genuchten model and the Origin software, Results The curves were fitted and the SWCC curves of Chengdu clay were obtained. The reference values ​​of fitting parameters were given. With the help of the CT-3031 conductivity meter, the soil sample’s permeate suction was measured. The matrix suction was equal to the total suction minus the suction force, and the soil suction-moisture content curve was obtained indirectly. Compared with the filter paper method, the SWCC curve obtained from the same soil samples was obtained, the suction value measured by the cold mirror dew point technique at the same moisture content was lower than the value measured by the filter paper method, which was consistent with the relevant conclusions from foreign literature. Test suction is fast, convenient, accurate and so on. It is pointed out that the chilled mirror dew point technique is feasible in the application of unsaturated clay test in unsaturated Chengdu and can be generalized to the suction test in the related fields of geotechnical engineering in China.