【作者】 詹卫华；

【导师】 黄冠华；

【作者基本信息】 中国农业大学 ， 农业水土工程， 2000， 硕士

【摘要】 定量研究土壤形态特征，描述土壤粒径与孔隙分布状态的主要目的之一是精确刻划士壤水流特征，为揭示和模拟土壤水流与溶质运移转化规律提供可靠的参数和理论支持。分形理论应用于土壤学科，使定量描述土壤结构特征及土壤水力特性的复杂性质成为可能。近十多年来，国内外学者分别从孔隙、粒径、颗粒体积及表面分形维数描述土壤结构，应用Mefiger和Sierpinski孔隙分形模型表征土壤水力特性参数分形特征。本文应用分形理论对土壤水力特性参数（主要包括土壤水分特征曲线、土壤水力传导度、土壤水分扩散度）进行了田间试验和理论分析。根据粒径的重量分析方法，结合土壤机械组成分析资料计算出不同地区的10种土壤结构分形维数从2．489至2．896，同时按照国际制土壤质地划分标准计算出各种土壤的分形维数范围，结果表明：分形维数的大小反映了土壤质地中粘粒、粉粒和砂粒的含量变化，随粘粒含量的增多分形维数增大，随砂粒含量的增多分形维数减小；应用 aenser结构模型，推导出土壤水分特征曲线的分形特征，并拟合出土壤水力传导度及土壤水分扩散度的经验关系式；将土壤水分特征曲线及土壤水分扩散度的实测资料拟合出的分形维数与土壤结构分形维数比较，结果表明几乎相等，即土壤水力特性参数的分形特征可由土壤结构分形维数来表示；根据土壤特性空间变异结构具有自相似特征，应用变差函数的乘幂模型对土壤特性的空间变异特征进行了初步的分析研究。更多还原

【Abstract】 Numerous empirical models exist for soil hydraulic properties including soil water retention curve, unsaturated hydraulic conductivity and difiusivity. It has generally been recognized that the empirical fitting coefficients in these models are somehow related to soil texture. By using the concept of fractal geometry, Tyler and Wheatcraft (1990) proposed a physical conceptual model for soil texture and pore structure, and then a two-dimension fractal model for soil water retention curve was derived. This model is related to the intrinsic nature of the fractal porous structure. In this paper, the soil hydraulic properties parameters were studied by field experimentand theoretical analyses. The structures of ten different soils were tested with the method of particle-mass distribution. Results indicate that the fractal dimension of soil structure fractal changes from 2.489 to 2.896, and the change in fractal dimension implies the change of content of clay, silt and sand for the soil particle. A three-dimensional fractal model for soil water retention curve was derived with Menger Sponge model on the based of Tyler and Wheatcrafts’ theory, and the relative permeability functions of Burdine and Mualem are also shown to be fractal and directly related to the fractal of water retention curve. The fractal dimension in these models are calibrated with experimental data for ten soils, and the values of the calibrated fractal dimension are approximately equal to those fractal dimension of soil structure. And therefore, the derived models incorporated with soil structure fractal dimension can be used to describe the real soil hydraulic properties. At the same time, the spatial variation of soil properties was primarily studied by using the fractal model in power form, and results were synthetically analyzed.更多还原