摘要
黄土台塬地带频发的滑坡灾害与农业灌溉活动密切相关。为研究水分在原位黄土中的入渗规律,在陕西泾阳南塬开展了场地直径为20 m的灌溉入渗试验,分析了浸水过程中入渗水量,土体体积含水率、基质吸力和孔隙气压的变化规律,揭示了灌溉水在原位黄土中的入渗过程。监测结果表明:①持续灌溉条件下,湿润锋下移深度大于11.0 m,初始入渗率较高,随后降低并趋于稳定,稳定入渗率略小于表层土体的渗透系数。②马兰黄土中存在平行于塬边的竖向裂隙,裂隙最大宽度约为15.0 mm,灌溉水易沿贯通裂隙产生优势入渗。③第一层古土壤(S1)为透水性地层,当湿润锋抵达S_(1)下部时下移受阻而移动速率降低,产生最高水头为44 cm的瞬态滞水。④灌溉水入渗过程中孔隙气体被压缩而气压升高,在湿润锋到达前产生气阻效应;不同深度处土体的最大孔隙气压为1.1~4.3 kPa。
Frequent irrigation activities have triggered numerous landslide hazards along the margins of the loess platform.For a better understanding of the process of irrigation water penetrating through stratified loess sediments,a full-scale field infiltration experiment with a diameter of 20 m is conducted on the South Jingyang tableland,Shaanxi Province,China.The amount of irrigation water,volumetric water content,matric suction and pore-air pressure are monitored to reveal the infiltration process of loess sediments.The monitoring results can be drawn as follows:(1)The propagation of wetting front is more than 11 m under the ponding condition.The infiltration rate is initially high,then decreases gradually and finally approaches a constant value less than the saturated hydraulic conductivity of the soil in shallow depth.(2)The vertical fractures parallelling to the edge of the tableland in Malan loess are revealed through vertical shaft,which has an aperture of less than 15 mm.The preferential flow is observed in the preferential path of the Malan loess layer.(3)The first paleosol layer(S_(1))is proved to be permeable,and a transient perched water with a waterhead less than 44 cm is developed above the lower part of S_(1).(4)The pore-air in soil is compressed,and an air entrapment ahead of wetting front is observed during wetting period.The maximum pore-air pressure measured in loess sediments varies from 1.1 kPa to 4.3 kPa.
作者
赵志强
戴福初
闵弘
涂新斌
ZHAO Zhi-qiang;DAI Fu-chu;MIN Hong;TU Xin-bin(Faculty of Architecture,Civil and Transportation Engineering,Beijing University of Technology,Beijing 100124,China;State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan 430071,China;State Grid Economic and Technological Research Institute Co.,Ltd.,Beijing 102209,China)
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2022年第3期569-575,F0003,共8页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金重大项目(41790440)。
关键词
黄土
原位监测
入渗过程
湿润锋
优势入渗
气阻效应
loess
field monitoring
infiltration process
wetting front
preferential flow
air entrapment
作者简介
赵志强(1989-),男,博士研究生,主要从事灌溉作用下黄土滑坡诱发机制研究。E-mail:957114686@qq.com;通信作者:戴福初,E-mail:daifc@bjut.edu.cn。
