单向冻结下渠基土的锅盖效应试验研究  

Experimental Study on Pot Lid Effect of Canal Soil Under Unidirectional Freezing

作　　者：唐少容[1,2,3] 柯德秀 杨强 高天源 TANG Shaorong;KE Dexiu;YANG Qiang;GAO Tianyuan(College of Civil and Hydraulic Engineering,Ningxia University,Yinchuan 750021,China;Ningxia Research Center of Technology on Water-Saving Irrigation and Water Resources Regulation,Yinchuan 750021,China;Engineering Research Center for Efficient Utilization of Water Resources in Modern Agriculture on Arid Regions,Yinchuan 750021,China)

机构地区：[1]宁夏大学土木与水利工程学院,宁夏银川750021 [2]宁夏节水灌溉与水资源调控工程技术研究中心,宁夏银川750021 [3]旱区现代农业水资源高效利用教育部工程研究中心,宁夏银川750021

出　　处：《人民黄河》2024年第3期109-113,120,共6页Yellow River

基　　金：宁夏回族自治区重点研发计划项目(2021BEG03023);宁夏高等学校一流学科建设项目(NXYLXK2021A03);宁夏大学学生创新创业训练项目(202310749586)。

摘　　要：寒旱区刚柔复合衬砌渠道铺设的复合土工膜阻碍土体冻结过程中的水分蒸发,出现复合土工膜下土体增水的现象,即“锅盖效应”。为探究土体的锅盖效应发生机制和规律,制备不同含水率的土柱试样进行单向冻结试验,分析复合土工膜对土柱温度场和水分场的影响。研究表明:有复合土工膜覆盖土柱的降温速率及土层间温差均小于未覆盖复合土工膜的土柱;冻结过程中,未覆盖复合土工膜的土柱底部水分通过土体孔隙通道不断向顶层迁移补充后蒸发,整个土柱含水率降低,且呈不均匀状分布;而有复合土工膜覆盖的土柱,在水分迁移和锅盖效应作用下,底部土体含水率降低,膜下顶层土体含水率显著增加,且膜下结冰,表明复合土工膜使土体在冻结过程中产生明显的锅盖效应。初始含水率不同的土柱受锅盖效应影响后产生的水分迁移量和形态存在差异,初始含水率较小的土柱顶层含水率的增加以气态水迁移为主,初始含水率较大的土柱含水率的增加则以液态水迁移为主。Water evaporation during soil freezing is hindered by the composite geomembrane laid in rigid⁃flexible composite lining canals in cold and arid regions,and the phenomenon of soil water increase under the composite geomembrane,that is,the“pot lid effect”.In order to explore the mechanism and rule of the pot lid effect of soil,soil columns with different moisture content were prepared and unidirectional freezing test was carried out.The influence of composite geomembrane on soil column temperature and water field was analyzed.The results show that the cooling rate of soil column covered with composite geomembrane and the temperature difference between soil layers are lower than that of soil column without composite geomembrane.During the freezing process,the water at the bottom of the soil column without the composite geomembrane is transferred to the top continuously through the pore channel of the soil,and then evaporates,and the water content of the whole soil column decreases,and the distribution is uneven.For soil columns covered by composite geomembrane,the moisture content of the soil at the bottom decreases under the action of water migration and pot cover effect,while the moisture content of the top soil under the membrane increases significantly,and the pot cover effect under the membrane is frozen,which indicates that the soil under the composite geomembrane has an obvious pot cover effect during the freezing process.Soil columns with different initial moisture content have different amounts and forms of water transfer under the influence of pot lid effect.The increase of water transfer in the top layer of soil column with small initial moisture content is mainly caused by gaseous water transfer,while the increase in water transfer in soil column with large initial moisture content is mainly caused by liquid water transfer.

关 键 词：刚柔复合衬砌渠道 锅盖效应 单向冻结 温度场 水气迁移 

分 类 号：TV16[水利工程]