\r罗 汀，陈 含，姚仰平，陈 伟\r
\r
AuthorsHTML:\r罗 汀，陈 含，姚仰平，陈 伟\r
\r
AuthorsListE:\rLuo Ting，Chen Han，Yao Yangping，Chen Wei\r
\r
AuthorsHTMLE:\rLuo Ting，Chen Han，Yao Yangping，Chen Wei\r
\r
Unit:\r北京航空航天大学交通科学与工程学院，北京 100083\r
\r
Unit_EngLish:\rSchool of Transportation Science and Engineering，Beihang University，Beijing 100083，China\r
\r
Abstract_Chinese:\r锅盖效应是指土中的水汽迁移被覆盖层所阻挡，水汽在冷凝或凝华作用下在覆盖层下聚集的现象．为了研究寒区路基土的锅盖效应气态水迁移规律并分析其作用机理，利用自行研制的锅盖效应试验设备，采用取自北京大兴国际机场的粉质黏土试样进行了一系列试验，研究了温差、初始含水率和试验时间对于锅盖效应的影响．试验结果表明：土样上下边界存在温差时，水汽会向低温区迁移，使土样上部含水率增加，温差越大，土样上部水分增加量越大，且水汽越容易补充进土样；土样顶部为正温时，含水率只在覆盖层下出现最大值，土样顶部为负温时，含水率不仅在覆盖层下出现最大值，而且在冻结锋面处也会出现峰值；初始含水率较低时，土体中的水分迁移以气态
水迁移为主，较高时以液态水迁移为主，初始含水率适中时，以混合态水迁移为主，气态水迁移时，试样能够从水源吸收水汽使土样总水量增加；进行了试验时间为30 d 的冻结条件下的气态水迁移试验，发现试验过程中水汽不断补充进土样，土样上部水量和总水量均持续增加，试验结束后覆盖层下产生了凝华冰层，含水率接近饱和．试验结果说明锅盖效应可以造成寒区实际路基土的含水率大幅提高，使之存在工程病害隐患．\r
\r
Abstract_English:\rPot-cover effect refers to the phenomenon of moisture accumulation beneath a pavement under condensation or desublimation because the pavement obstructs vapor transfer in the soil．A series of tests were carried out with silty clay from Beijing Daxing International Airport using a self-developed pot-cover effect test equipment to study the vapor transfer law and analyze the pot-cover effect mechanism of the actual subgrade soil in cold regions．The influences of temperature differences，initial water content，and test period on the pot-cover effect were revealed．The test results are as follows：under temperature difference，vapor migrated to the low-temperature zone，which will cause the increase in topsoil moisture．With the increase in temperature difference，the water contents in the upper part of samples increased，and the water vapor migrated into the samples more easily．When the top temperature was positive，the peak value of water content only occurred under the cover．When the top temperature was negative，a second peak value occurred at the freezing front．When the initial water content was lower，gaseous water migration dominated in the samples．The liquid water migration dominated when the initial water content was higher，and the mixed water migration dominated when the initial water content was moderate．Vapor transfer can result in water vapor absorption from water source and increase the total soil moisture．A 30-day vapor transfer test was carried out under freezing condition．The result showed that water vapor continuously migrated into the soil samples．The water quantity of the upper part of the sample and the whole sample both increased during the test．After the test，an ice layer caused by vapor desublimation formed under the cover，and the soil nearly saturated there．The test results indicate that the pot-cover effect can cause significant increase in the actual subgrade soil moisture in cold regions and
may lead to engineering diseases．\r
\r
Keyword_Chinese:锅盖效应；气态水迁移；路基土；寒区；含水率\r

Keywords_English:pot-cover effect；vapor transfer；subgrade soil；cold regions；water content\r


PDF全文下载地址:http://xbzrb.tju.edu.cn/#/digest?ArticleID=6288