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A Fractal Study on Soil Structure and Soil Water Movement Model

Author: LiuYunPeng
Tutor: WangGuoDong
School: Northwest University of Science and Technology
Course: Soil
Keywords: The particle size distribution fractal dimension , fractal dimension Water characteristic curve Hydraulic conductivity Pore ??cross-sectional shape
CLC: S152
Type: Master's thesis
Year: 2002
Downloads: 793
Quote: 15
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Abstract

Shaanxi four different soil textures, particle size distribution and water characteristic curves and saturated and unsaturated hydraulic conductivity relationship was. Fractal theory and the impact of the movement of the water retention of soil texture and structural condition, the following conclusions: 1. Cumulative mass of soil particle size distribution fractal characteristics based on the number of particles, particle size distribution fractal dimension to resolve to determine particle mass, particle size distribution fractal dimension, and can more easily determine the particle size distribution fractal dimension number. In theory further indicates the particle size Bouvet number of physical significance, namely: particle size distribution the fractal dimension D_P the range of 0 to 3, and its size reflects the different texture of the soil particles fill. Tested four kinds of soil particle size distribution exhibit fractal characteristics, demonstrate the finer texture, particle size distribution fractal dimension of the closer 3. 2. The parameters describe the condition of soil texture and size distribution fractal dimension of a certain relevance, and pointed out that the size distribution of the fractal dimension can be used as an indicator of the evaluation of the soil texture conditions. Tested four soil particle size distribution of the fractal dimension of soil clay content (<0.001mm) there is a significant linear correlation, manifested as higher clay content, particle size distribution of the fractal dimension of the larger; tablets has a significant linear correlation between the fractal dimension and particle mean geometric diameter size distribution, but it is almost linear correlation with the average weight diameter. Particle size distribution fractal dimension the weak soil particle uniformity index Iu linear relationship, indicating that soil texture is affected not only by the complexity of the particle size, especially the domination of the small particle size of the soil particles content, but also by the various grain size distribution of soil particles impact; 3. Four soil moisture characteristic curve obtained by the AP model can better reflect the relationship between soil water potential and water content of the soil actual low suction force range segment. But in the larger high suction segment AP model predictions with the actual deviation, the actual the Unicom situation, taking into account the soil pore the correct AP model, four of the test in the entire water content range of soil moisture characteristic curve better fitting. 4. The the new Fractal dimension - fractal dimension of soil structure D_S also reflect soil fill position reflect the soil voids Unicom situation. Changes in of difference δ fractal dimension of soil structure the number D_S its particle size distribution the fractal dimension D_P the soil moisture characteristic curve of different texture is sensitive, D_S, and δ two new indicators for the quantitative description of the soil structure , D_S reflect the structural condition of the soil texture, and δ reflect changes in the structure of the same germplasm soil. 5. The new structure of the soil fractal dimension applied to the description of the saturated hydraulic conductivity and unsaturated hydraulic conductivity of soil water movement parameters forecast accuracy With a large extent, to improve. Under low moisture conditions, finer in texture and pore radius and porosity actual Unicom condition of the water movement under low water content; coarse texture soil, in addition to the actual the Unicom situation impact the pore radius and pore Also subject to the influence of the cross-sectional shape and the change of the pore channels. Coarse pore channel cross-sectional shape and change on water movement greater impact, the smaller channel cross-sectional shape of the gap is less water movement. Correction pore geometry on water movement, further consider the pore-sectional shape factor of soil water movement can be more accurately predict soil water movement parameters.

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