基于分形理论模拟花岗岩崩岗剖面土壤水分特征曲线

发布时间：2019-01-30 09:30

【摘要】：崩岗是我国南方花岗岩地区特殊的土壤侵蚀现象,给山区经济造成了严重的影响。为了探索南方花岗岩地区崩岗侵蚀剖面的水分特性,明确水分与崩岗发育的关系,本研究采用野外调查采样与室内分析的方法,运用土壤粒径分形理论,并结合Brooks and Corey模型,模拟花岗岩崩岗剖面土壤水分特征曲线。选择通城县花岗岩崩岗剖面5个层次(表土层、红土层、过渡层、砂土层和碎屑层)采集土样,通过对土壤粒径分布和土壤含水量的测定,分析分形维数与土壤粒径之间的关系。同时,应用土壤粒径分形理论,模拟土壤水分特征曲线,基于估算结果与实测结果的比较,探讨分形方法估算土壤水分特征曲线的可行性。结果表明:崩岗剖面土壤黏粒质量分数越大,土壤粒径分维值越大;土壤粒径分维值越大,土壤水分特征曲线的分维值则越大,两者之间线性关系较好;运用分形理论,模拟土壤水分特征曲线的预测值与实测值具有良好的一致性,模拟结果的精度随土层的深度增加而增加,模拟效果以土壤黏粒和粉粒质量分数较少、砂粒质量分数较多的土壤效果较好。研究结果为花岗岩崩岗机理的探索奠定了基础,对崩岗水分的研究具有指导意义。
[Abstract]:Collapse is a special phenomenon of soil erosion in granite area of southern China, which has a serious impact on the economy of mountainous area. In order to explore the water characteristics of collapse erosion profile in granite area of southern China, and to clarify the relationship between water content and collapse development, the field investigation and indoor analysis were used in this study. The fractal theory of soil particle size was used and combined with Brooks and Corey model. The soil moisture characteristic curve of granite caving section is simulated. Five layers (topsoil, red soil, transitional layer, sand layer and clastic layer) of granite caving section in Tongcheng County were selected to collect soil samples, and the particle size distribution and soil moisture content were measured. The relationship between fractal dimension and soil particle size was analyzed. At the same time, the fractal theory of soil particle size is applied to simulate the characteristic curve of soil moisture. Based on the comparison between the estimated results and the measured results, the feasibility of estimating the characteristic curve of soil moisture by fractal method is discussed. The results showed that the larger the mass fraction of soil clay, the larger the fractal dimension of soil particle size, the larger the fractal dimension of soil water characteristic curve, and the better the linear relationship between them. Using fractal theory, the predicted value of simulated soil moisture characteristic curve is in good agreement with the measured value. The accuracy of simulation results increases with the increase of soil depth, and the simulation effect is less than that of soil clay and silt mass fraction. Soil with more sand mass fraction has better effect. The results lay a foundation for the exploration of the mechanism of granite collapse, and have a guiding significance for the study of water content in granite collapse.
【作者单位】：华中农业大学水土保持研究中心;
【基金】：国家自然科学基金“花岗岩红壤优先流及其与崩岗侵蚀发育的关系”(41571258) 国家科技支撑计划子课题“红壤崩岗侵蚀区农田质量保护与崩岗治理技术与示范”(2011BAD31B04)
【分类号】：S152.7

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