夹砂层土壤Green-Ampt入渗模型的改进与验证  

Improvement and verification of Green-Ampt model for sand-layered soil

作　　者：范严伟[1,2] 赵文举[1] 王昱[1] 毕贵权[1] 

机构地区：[1]兰州理工大学能源与动力工程学院,兰州730050 [2]兰州大学西部灾害与环境力学教育部重点实验室,兰州730000

出　　处：《农业工程学报》2015年第5期93-99,共7页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金项目(51409137);国家自然科学基金项目(51269008);甘肃省自然科学基金项目(145RJYA293)

摘　　要：对于土层夹砂结构,湿润锋穿过砂层上界面时,入渗率变为稳渗率。为确定各因素下夹砂层土壤的稳渗率,在Green-Ampt入渗模型基础上,引入导水度系数(小于1)来量化上层土壤的导水程度,建立了改进的夹砂层土壤Green-Ampt入渗模型。采用HYDRUS-1D软件,模拟了不同土壤质地、初始含水率、压力水头、砂层埋深和砂层厚度条件下的稳渗过程,根据模拟结果分析了夹砂层土壤的入渗规律及其影响因素,稳渗率主要受土壤质地、压力水头和砂层埋深的影响。在相同压力水头、初始含水率和砂层厚度下模拟获得不同砂层埋深的稳渗率,并采用改进的Green-Ampt入渗模型拟合,求得导水度系数和进水吸力值。分析发现导水度系数变化较小,为简化计算,取其平均值0.95。在此基础上,提出了由土壤物理特性参数进气值倒数估算进水吸力的计算公式。利用秦王川地区的夹砂层土壤积水入渗试验及已有文献资料验证所建模型的有效性,结果表明所建模型待定参数少,计算误差基本在5%以内,且试验设计较简单,可为农田水分管理及工程防渗技术提供理论依据。In the northwest of China, soil structure with sand interlayer is a common soil configuration. For soil structure with sand interlayer, infiltration rate will turn to steady infiltration rate when wetting front passes through the upper interface of sand layer. Normally, in the traditional Green-Ampt infiltration model, the water entry suction is difficult to determine. Furthermore, due to the hydraulic conductivity of wetting pattern is assumed to the saturated hydraulic conductivity of upper soil in the model, the error exists when calculating the steady infiltration rate of soil with sand interlayer. In order to compute the steady infiltration rate of the soil with sand interlayer accurately and conveniently, hydraulic conductivity coefficient, which was less than 1, was introduced to quantify the extent of water conductivity for upper layer soil on the basis of Green-Ampt infiltration model. More importantly, under the influence of various factors, the improved Green-Ampt infiltration model for soil with sand interlayer was set up, which included the undetermined parameters to the hydraulic conductivity coefficient and water entry suction. With the HYDRUS-1D software, the procedure of steady infiltration under various factors including soil texture, soil initial water content, pressure head, sand depth and sand thickness was simulated. At the same time, the law of infiltration and its influencing factors were analyzed according to the simulation results. The results showed that steady infiltration rate was mostly influenced by soil texture, pressure head and sand depth, but the steady infiltration rate of soil with sand interlayer was not affected by the soil initial water content and the thickness of sand interlayer. In view of the above, the steady infiltration rate could be acquired through simulation by changing sand depth while remaining pressure head, initial water content and sand thickness constant. Then the values of hydraulic conductivity coefficient and water entry suction were determined by fitting

关 键 词：入渗 数值分析 验证 层状夹砂土 稳渗率 改进Green-Ampt模型 

分 类 号：S152.7[农业科学—土壤学]