摘要
为研究强降雨作用下水分在原位黄土中的入渗规律,在小浪底北岸灌区隧道冒顶灾害附近取得高120 cm、直径60 cm的原状土柱,并基于土柱开展多次降雨入渗模拟试验,监测得到土柱不同深度处土体含水量变化规律,揭示水分在原位黄土中的入渗过程。结果表明:试验初期土柱表层土体初始含水量低、基质势高,水分入渗速率快,而深部土体湿润锋锋面含水量变化平稳、基质势低,水分入渗速率慢;多次强降雨叠加作用下,土体导水性增强、湿润锋下移速率显著增加;基于监测数据分阶段建立幂指数和线性形式的湿润锋运动模型,可用于预测考虑强降雨叠加效应下原状黄土中湿润锋的运动过程。
Loess is a layered sediment formed in semi-arid climates,characterized by its large thickness and loose structure,making it prone to geological disasters.Continuous heavy rainfall infiltrating loess areas increases soil moisture content,reduces matric suction,and decreases shear strength.Additionally,rainfall infiltration raises the groundwater level,causing instability and potential failure once the saturation strength reaches a critical point.Therefore,studying water infiltration under heavy rainfall is essential to understand the triggering mechanisms of geological disasters in loess regions and to provide a scientific basis for disaster prevention and mitigation.To investigate the field infiltration process of in-situ loess during heavy rainfall,an undisturbed soil column measuring 120 cm in height and 60 cm in diameter was collected near a roof collapse site in a tunnel located in the North Bank Irrigation Area of Xiaolangdi.The soil sample,classified as Middle Pleistocene(Q2)loess,is brownishyellow,features needle-shaped pores,and has uniform properties.Five moisture meters were installed at depths of 10 cm,30 cm,50 cm,80 cm,and 110 cm within the soil column.Subsequently,six rainfall infiltration simulation experiments were conducted to monitor changes in soil volumetric moisture content at different depths,revealing the moisture infiltration process in the in-situ loess.Considering the water infiltration capacity and moisture content over time,the infiltration process can be divided into five stages:unsaturated infiltration,water saturation infiltration,rainfall superposition infiltration,water saturation transport,and dehumidification.During the experiments,the wetting front in the soil column was observed to move downward continuously.Based on the initial response time recorded by the moisture meters at various depths,the wetting front’s position over time was determined,and a staged motion model of the wetting front under multiple rainfall conditions was developed.In the initial unsaturated infiltration stage,the wetting front moves rapidly downward initially,then its rate stabilizes.The infiltration model fitted during this stage follows a power function,similar to the classical empirical model of Kostiakov,with an R2 value of 0.871.The second stage involves the continuous downward movement of the wetting front under multiple rainfall events,with ponding observed on the surface.Here,the wetting front depth increases linearly over time,with a high correlation coefficient of 0.972.Based on the dynamic response of volumetric moisture content at different depths,the initial soil moisture is relatively low,and the matrix potential is high.Early in rainfall,water rapidly infiltrates downward due to gravity and matric potential.As the wetting front penetrates deeper,the matric potential decreases,slowing the rate of moisture increase.Analyzing the cumulative effects of multiple rainfall events shows that,after a single event,soil moisture decreases as the wetting front moves downward but rapidly increases after subsequent rainfall,due to increased soil moisture content and hydraulic conductivity influenced by prior rainfall.In summary,the staged rainfall infiltration model developed from this study's monitoring data effectively predicts the movement of the wetting front in undisturbed loess under overlapping rainfall conditions.
作者
申继先
赵本超
王探宇
董金玉
王波波
赵志强
葛玉
周海韵
SHEN Jixian;ZHAO Benchao;WANG Tanyu;DONG Jinyu;WANG Bobo;ZHAO Zhiqiang;GE Yu;ZHOU Haiyun(Henan Haihe River Basin Water Affairs Center,Zhengzhou 450004,China;North China University of Water Resources and Electric Power,Zhengzhou 450046,China;Henan Water Conservancy Survey Co.,Ltd.,Zhengzhou 450008,China;Control Engineering Technology Institute of Special Geotechnical Environment of Henan,Zhengzhou 450008,China;Henan Water Conservaney Investment Group Xiaolangdi North Bank lrrigation District Engineering Co.,Ltd.,Zhengzhou 450004,China)
出处
《南水北调与水利科技(中英文)》
北大核心
2025年第4期997-1006,共10页
South-to-North Water Transfers and Water Science & Technology
基金
河南省重点研发专项项目(241111322900)
河南省水利厅2022年度水利科技公关项目(GG202268)
河南省科技攻关项目(252102320011)。
关键词
强降雨
原状土柱
体积含水量
入渗过程
湿润锋
运动模型
heavy rainfall
undisturbed soil column
volumetric water content
infiltration process
wetting front
movement model
