摘要
以壤土为研究对象,将十八胺基伯胺作为斥水剂掺入天然风干重塑壤土中,配置了不同十八烷基伯胺含量和初始含水率的改性试样,采用滴水穿透时间法测定了改性壤土的斥水等级,提出并获得了改性壤土的临界含水率,分析了十八烷基伯胺含量、壤土斥水等级、初始含水率的关系。在此基础上,采用全自动三轴渗透仪,开展了改性壤土在不同水头差作用下的渗透试验,揭示了不同斥水等级壤土的入渗性能,获得了改性壤土的稳定入渗率。结果表明:十八烷基伯胺含量和土壤含水率是影响土壤斥水性的重要因素。十八烷基伯胺含量越高,土壤斥水等级越大,上限含水率越低,而下限含水率越高。土壤斥水等级相同时,初始入渗速率受水头差影响较小,如十八胺基伯胺质量分数为 0.6%的土壤,20 和 60 kPa 水头差条件下其初始入渗速率分别为 0.210 和 0.238 cm/s;入渗持续一段时间后,入渗速率突然降低,降至0.005 cm/s,进入稳定入渗阶段。土壤斥水性越强,稳定入渗速率和稳定入渗率均呈下降趋势,壤土防渗效果越好。起始出渗时间随水头差的增大而减小,随土壤斥水性的增大而增大。上述研究成果可为斥水性土壤应用于土木水利工程领域提供试验基础。
This study aimed to analyze water repellency and infiltration performance of soils with octadecylamine addition. Air-dried remolded loam was mixed with octadecylamine to obtain water repellent loam. A total 5 kinds of loam with octadecylamine content of 0.2%, 0.4%, 0.6%, 0.8% and 1.0% were prepared. For each loam with a certain octadecylamine content, 16 samples with different initial moisture content were then prepared. The water repelling of water repellent loam was determined by water drop penetration time (WDPT), and the critical moisture content of water repellent loam was proposed. Then the permeability tests of water repellent loam under different water head differences were carried out by using a triaxial permeameter. The relationship between octadecylamine content, seepage discharge and water head differences was analyzed, and the permeability coefficient of water repellent loam was obtained. The octadecylamine and soil moisture content were important factors affecting soil water repellency and the higher octadecylamine mass fractions had the stronger water repellency of loam, the lower moisture content of upper limit, and the higher moisture content of lower limit. When the moisture content was less than 12%, the drop penetration time of loam with octadecylamine content of 0.2% and 0.4% was less than 5 s, which showed hydrophilicity. When the moisture content of loam increased to 21%, the drop penetration time of loam increased rapidly to 3 611 and 4 012 s, respectively. That means the corresponding water repelling of loam changed from hydrophilicity to extreme level. The drop penetration time of loam soil with moisture content between 21% and 25% was more than 3 600s, which showed extreme level. When the moisture content increased from 25% to 32%(saturation), the water repellency of loam decreased rapidly from extreme to hydrophilicity. In loam with natural air-dried moisture content, the drop penetration time of loam with octadecylamine content of 0.6% and 0.8% were 731 s and 2 584 s, which showed severe level. With the increasing of moisture content, the drop penetration time increased rapidly to 9 345 s (moisture content of 23.1%) and 12 364 s (moisture content of 21.6%), which showed extreme levels. Then the drop penetration time decreased rapidly and the water repellency disappeared completely at saturation. The drop penetration time of natural air-dried loam was 4 886 s with octadecylamine content of 1.0%, which showed extreme level. With the increasing of moisture content, the drop penetration time also increased rapidly. The maximums of drop penetration time were more than 18 000s (moisture content of 19.3%, 20.0% and 23.7%) which showed extreme levels. When the moisture content increased to 26.8%, the drop penetration time decreased rapidly to 9 346 s, and the water repellency disappeared completely at saturation. For loam with octadecylamine content of 0.2% and 0.4%, the upper limits of moisture content were 11.1% and 10.8%, and the lower limits of moisture content were 23.9% and 24.1%, respectively. For loam with octadecylamine contents of 0.6%, 0.8% and 1.0%, the upper limits of moisture content were 3.5%, 2.8% and 2.0%, and the lower limits of moisture content were 26.3%, 27.1% and 27.3%, respectively. When the octadecylamine content were the same, the initial infiltration rates was less affected by water head differences. After a period of time, the infiltration rates were decreased suddenly and kept stable. The larger water head differences had the higher stable infiltration rates. When the water repellency of soils changed from wettable to extreme level, the stable infiltration rate gradually decreased. The mutation time of infiltration was shortened with the increasing of water head differences. When the octadecylamine content were low (0%, 0.2% and 0.4%), the permeability coefficients were greatly affected by the water head differences: the greater the water head differences had the smaller permeability coefficients. When the octadecylamine content were high (0.6%, 0.8% and 1.0%), the permeability coefficients were basically not affected by the water head differences. When the octadecylamine content was 0.8% and the water head difference was 20 kPa, the water hardly infiltrated into loam which showed complete impermeability. The results can provide theoretical support to analysis on hydrophobized soil and its application in civil and hydraulic engineering.
作者
吴珺华
林辉
刘嘉铭
王茂胜
杨松
Junhua;Lin Hui;Liu Jiaming;Wang Maosheng;Yang Song(College of Civil Engineering and Architecture, Nanchang Hangkong University, Nanchang 330063, China;College of Water Conservancy, Yunnan Agricultural University, Kunming 650201, China)
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2019年第13期122-128,共7页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家自然科学基金项目（51869013、41867038）
江西省自然科学基金项目（20181BAB216033）
江西省教育厅科技项目（GJJ180530）
南昌航空大学研究生创新基金项目（YC2018070）
