土壤水分特征曲线的推求方法

发布时间：2018-03-20 16:06

本文选题：土壤水分特征曲线　切入点：剖面含水率　出处：《长安大学》2016年硕士论文　论文类型：学位论文

【摘要】：土壤水分特征曲线是土壤最基本的参数之一,它是描述土壤水的基质势或者吸力随着土壤含水率变化的关系曲线。土壤水分特征曲线对研究土壤水滞留、运移、非饱和土的渗透系数等均有重要作用,对土壤污染、地面沉降、边坡失稳等具有重要意义。然而土壤水分特征曲线是高度非线性的,难以从理论上推导其数学表达式,而且直接测量土壤水分特征曲线耗时长、成本高。因此,对土壤水分特征曲线进行解析并预测具有重大意义。本文以土壤水分特征曲线的推求方法为研究目标,运用物理经验法中Arya-Paris模型(A-P方法)、分形几何法中Brooks-Corey模型(B-C方法)以及剖面含水率推求土壤水分特征曲线方法对中砂、细砂等六种土样的土壤水分特征曲线进行解析及预测,并得到以下结论:1.利用不同土壤颗粒累积曲线模型对中砂、细砂等六种土壤进行拟合,就拟合效果而言:Gompertz模型、Mlog模型Weibull模型、Morgan模型、HP模型、S2P模型以、LS模型Fredlund模型Jaky模型,综合分析后表明,Gompertz模型、Mlog模型比较适合描述土壤颗粒累积曲线,这为A-P法和B-C法的计算做了必要的基础准备。2.以土壤颗粒分布为基础,运用物理经验法中A-P法、分形几何法中B-C法对中砂、细砂等六种土样进行了土壤水分特征曲线的间接预测。结果表明A-P法比较适合推求中等粒径土壤(比如粉砂)的土壤水分特征曲线,B-C法与之相反,对较小或较大粒径土壤推求结果较好。3.通过Van Genuchten模型、Gardner模型及非饱和垂直一维达西定律推导了通量q,有效含水率Se等的理论关系,得到了Van Genuchten模型、Gardner模型的参数估算公式,并以此为基础,利用不同时刻剖面含水率,实现了Van Genuchten模型、Gardner模型的参数求解,验证结果表明这种方法所推求的土壤水分特征曲线具有较高精度。
[Abstract]:The characteristic curve of soil moisture is one of the most basic parameters of soil, it is the relation curve of describing the matrix potential or suction of soil water with the change of soil moisture content, the characteristic curve of soil moisture is used to study the retention and migration of soil water. The permeability coefficient of unsaturated soil plays an important role in soil pollution, land subsidence, slope instability and so on. However, the characteristic curve of soil moisture is highly nonlinear, so it is difficult to derive its mathematical expression theoretically. Therefore, it is of great significance to analyze and predict the characteristic curve of soil moisture. Using Arya-Paris model A-P method in physical experience method, Brooks-Corey model B-C method in fractal geometry method) and section moisture content calculating soil moisture characteristic curve method, the soil moisture characteristic curves of six kinds of soil samples, such as medium sand and fine sand, are analyzed and forecasted. The following conclusions are obtained: 1. Six kinds of soils, such as middle sand and fine sand, are fitted with different soil particle accumulation curve models. In terms of fitting effect, Weibull model of Mlog model and Weibull model of Morgan model and S2P model of HP model and S2P model are used as Jaky model of Fredlund model of LS model. The comprehensive analysis shows that the Gompertz model / Mlog model is more suitable to describe the soil particle accumulation curve, which makes necessary foundation preparation for the calculation of A-P method and B-C method. 2. Based on the distribution of soil particles, the A-P method is used in the physical experience method. In the fractal geometry method, B-C method is used to predict indirectly the soil moisture characteristic curves of six kinds of soil samples, such as medium sand and fine sand. The results show that A-P method is more suitable for calculating soil moisture characteristic curve of medium diameter soil (such as silt). The theoretical relationships of flux Q, effective moisture content se and so on are derived by Van Genuchten model and unsaturated vertical one-dimensional Darcy's law. The parameter estimation formulas of Van Genuchten model Gardner model are obtained. On the basis of this, the parameters of Van Genuchten model and Gardner model are solved by using the moisture content of different sections at different times. The results show that the characteristic curve of soil moisture obtained by this method has a high accuracy.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：S152.7

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