基于水平吸渗确定土壤水分扩散率的解析-修正法  

Analytical-modified method for determining soil water diffusivity based on horizontal imbibition

作　　者：帅嘉伟 龙平[1,2] 胡世丽[1] 王观石[1,2] 杨耀杰 罗嗣海[2] Shuai Jiawei;Long Ping;Hu Shili;Wang Guanshi;Yang Yaojie;Luo Sihai(School of Civil and Surveying Engineering,Jiangxi University of Science and Technology,Ganzhou 341000,China;Jiangxi Provincial Key Laboratory of Environmental Geotechnical and Engineering Disaster Control,Jiangxi University of Science and Technology,Ganzhou 341000,China)

机构地区：[1]江西理工大学土木与测绘工程学院,赣州341000 [2]江西理工大学江西省环境岩土与工程灾害控制重点实验室,赣州341000

出　　处：《农业工程学报》2022年第2期67-75,共9页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家重点研发计划(2019YFC1805101);国家自然基金项目(51874147,51774156);江西省教育厅科学技术研究项目(GJJ200870);江西理工大学高层次人才科研启动项目(205200100526);江西省自然科学基金资助项目(20192BAB2060048)。

摘　　要：准确测试土壤水分扩散率是研究水分在土壤中运移的关键之一。针对水平吸渗法测试土壤水分扩散率易受边界效应影响的问题,该研究构建解析-修正法,以提高测试结果的精度。假设第一类边界条件下,一维水平入渗Richards方程解的形式与其对应线性化方程的解析解相似,结合常数变易法,推导了一维水平入渗Richards方程的近似解析解。将有限长土柱中测点含水率随时间的变化数据分为受边界影响和不受边界影响两部分,采用近似解析解修正受边界影响的数据,再采用水平吸渗法确定土壤水分扩散率,以此建立测试土壤水分扩散率的解析-修正法,并通过数值模拟试验和室内试验讨论方法的合理性。结果表明,采用解析-修正法得到的土壤水分扩散率与真实值的决定系数均在0.900以上,室内试验不同测点间测试结果的决定系数均大于0.950。由此可见,该方法可以准确地确定土壤水分扩散率。研究可为土壤水运动的模拟提供可靠参数。Soil water diffusivity is one of the most important hydraulic properties during water transport in soil.It is very necessary to accurately estimate the key parameter in agricultural production.In this study,an analytical-correction approach was constructed to improve the accuracy of the soil water diffusivity using the horizontal imbibition,particularly considering the boundary effect.Assuming that the one-dimensional horizontal imbibition(Richards’s equation)was similar to the analytical solution of the linearized equation under the first types of boundary conditions,the approximate analytical solution was deduced using the constant variation.Hence,two parts were divided for the time-dependent change of the water content at the measuring point in the finite-length soil column,i.e.,with/without the boundary effect.Firstly,two parameters were determined to approximate the analytical solution without the boundary.Secondly,the experimental data were corrected by the analytical solution considering the boundary effect.Finally,the soil water diffusivity was determined to analyze the corrected data using the horizontal imbibition.As such,an analytical-correction approach was established to estimate the soil water diffusivity,further to verify the numerical and physical laboratory experiments.A Hydrus-1D software was used to simulate the migration process of water in six soil textures,including the loam sand,sandy loam,sandy clay loam,loam,silt clay,and silt.An indoor horizontal imbibition test was also carried out to verify the analytical solutions and analytical-correction model.The types of test soil were taken from the topsoil of ionic rare earth mines in Xinfeng County,Jiangxi Province,Xunwu County,Jiangxi Province,and Pingnan County,Fujian Province.The volumetric water content with time and coordinates were real-time monitored at the two measuring points(p;and p;,)using the FDS-100 water sensor.The results show that the analytical-correction approach can be widely expected to accurately correct the data caused b

关 键 词：土壤 特性 测试 水平吸渗 水分扩散率 

分 类 号：S152.7[农业科学—土壤学]