【作者】 辛琛；

【导师】 王全九； 樊军；

【作者基本信息】 西安理工大学 ， 农业水土工程， 2007， 硕士

【摘要】 本论文在总结国内外土壤水分运动特征理论与参数确定方法研究成果的基础上,采取理论分析与室内实验结合的方法,对不同负水头条件下四种土壤的水平一维吸渗、不同负水头条件下黄绵土的垂直一维吸渗及基于负水头条件下的土壤水分运动参数确定方法进行了研究。得到主要结果如下:1.进行不同负水头条件下四种土壤的水平一维吸渗实验,对不同负水头条件下的累积吸渗量、湿润锋和吸渗率随时间的变化关系进行比较分析。对Kostiakov经验模型、Philip模型和Wang等人推求的描述水平一维入渗过程中土壤水分运动各参量间关系在负水头条件下的适用性进行分析论证,并与0水头条件下所得结论进行比较,结果显示,上述公式可以用于描述负水头条件下土壤水分运动特征。2.以黄绵土为研究对象,进行不同负水头条件下的垂直一维吸渗实验,分析黄绵土在不同负水头条件下的累积吸渗量、湿润锋和吸渗率随时间变化关系。验证philip公式、Green-Ampt公式和Kostiakov经验公式在垂直一维吸渗过程中的适用性,并与0水头条件下所得结论进行对比,结果表明,传统的入渗公式也可以描述负水头条件下的垂直一维吸渗过程。3.利用负水头条件下的实测资料分析Philip模型与Kostiakov经验模型间关系,结果显示,负水头条件下二者仍然具有一致性。利用负水头条件下的实测资料验证Green-Ampt模型与Philip模型参数间的相关关系表达式,所得结果与0水头条件下所得的结论一致。4.根据负水头条件下的吸渗资料计算四种土壤的吸渗率,结果显示,随着负水头的增大,吸渗率逐渐减小。5.借助Wang的思想,根据Brooks-corey模型推求负水头条件下的土壤吸渗公式,并分析累积入渗量与湿润锋、吸渗率与湿润锋倒数和湿润锋与时间平方根间的关系。结果表明,在负水头条件下以上各参量间关系与Wang等人在正水头条件下所推求出的结果一致。6.根据邹朝望等人的基于两组负水头条件实验数据推求Brook-Corey模型参数的方法,对红胶土、黑垆土和塿土三种土壤的Brook-Corey模型参数进行推求,结果显示,利用所推参数计算出的水分特征曲线与利用离心机实测的水分特征曲线吻合较好。从理论上推求了负水头条件下,计算Van Genuchten模型参数的方法,为土壤水分运动的研究和参数的推求提供一种新的思路。更多还原

【Abstract】 Based on the literatures regarding the theory of soil water movement characteristics and hydraulic parameters determination, the methods to determine soil water movement parameters under negative hydraulic heads were discussed by theoretical analysis combined with laboratory infiltration experiments which consisted of horizontal one-dimensional infiltration for different texture soil and vertical one-dimensional infiltration for Huangmian soil. The results were as the follows:1. By horizontal one-dimensional infiltration experiments, the relationships of accumulated infiltration, wetting fronts and infiltration rates with elapsed time for different texture soils under different negative hydraulic heads were analyzed. The suitability of Kostiakov empirical model, Philip model and that developed by Wang(2000) which were used to describe the relationships of soil water movement parameters under horizontal one-dimensional infiltration for negative hydraulic heads conditions were tested and proved to be justifiable.2. Vertical one-dimensional infiltration experiments under different negative hydraulic heads with Huangmian soil were carried out , and the relationships of accumulated infiltration, wetting fronts and infiltration rates with time were also obtained. Meanwhile, the applicability of Philip infiltration equation, Green-Ampt infiltration equation and Kostiakov empirical formula which were used to traditioanlly characterize the vertical one–dimensional infiltration for 0 or positive water heads into negative heads was proved to be justifiable.3.Data obtained with experimental infiltration under negative hydraulic heads was employed to analyze the relationships of Philip model and Kostiakov empirical model. The results showed that they were identical in terms of negative hydraulic heads. The possible relationship between Green-Ampt model parameters and Philip model parameters under negative water heads was verified and found to be in good agreement with the situation under 0 hydraulic head.4. According to infiltration data under negative hydraulic heads, the soptivity of four soils was calculated. The results showed that sorptivity decreased with increasing negative hydraulic head.5. According to Wang (2000), soil infiltration equation could be derived under negative hydraulic heads based on Brooks-corey model and relationships of accumulated infiltration vs wetting fronts, infiltration ratesvs reciprocal wetting fronts and wetting fronts vs time square root were elucidated. The results proved that relationships of the above parameters derived from negative hydraulic heads were coincident with that derived by Wang(2000) under positive hydraulic heads.6.Brook-Corey model parameters of Hongjiao soil, Heilu soil and Lou soil were calculated with the method suggested by Zou (2006) which designed to analyzed infiltration data of two negative hydraulic heads. The result showed that soil moisture characteristic curve calculated based on above derived parameters agreed well with that measured by centrifuge. Van Genuchten model parameters can be theoretically derived under negative hydraulic heads, which provides a new approach to the research of soil water movement and parameter determination.更多还原