The fractal characteristics of soil grain-size in thick loess profile are closely related to its physical and hydrological characteristics. To reveal the relationship between loess grain-size distribution and its hydrological and physical characteristics, a profile of about 60 m was selected as the material. Systematic collection of samples along profile at 1 m intervals, and grain-size, moisture content, porosity, specific surface area, organic matter content and soil permeability were tested. The spatial heterogeneity of physical properties and grain-size fractal characteristics were analyzed using geostatistical methods and single and multifractal theories, respectively. The results showed that there was a strong spatial correlation between soil physical properties, but the moisture content was affected by certain human factors. The variation of fractal parameters with depth was affected by the climatic environment during its accumulation and development period. During loess accumulation period, the content of coarse particles in loess layers increased, and the concentration and symmetry of GSD increased, making D₁, D₂ and D₁/D₀ increase, and D, α₀, Δα and Δf(α) decrease. The relative content of fine particles and coarse particles in the soil affected the fractal characteristics and parameter sizes of GSD. Increase of singular spectrum parameters characterized the increase of soil heterogeneity, leading to the increase of specific surface area. The correlation between multifractal parameters and water content and organic matter was greatly affected by the depth and formation age of strata. There was a mutual response between GSD fractal characteristics and the soil permeability. The increase of D₁, D₂ and D₁/D₀ indicated strong soil permeability; the increase of α₀, Δα and Δf(α) reflected the high soil uniformity, which was not conducive to the occurrence of seepage process. The research results provided a case study and theoretical basis for the engineering construction and ecological restoration of the Loess Plateau.

厚黄土剖面土壤粒度的分形特征与其物理、水文特征密切相关。为揭示黄土粒度分布与其水文物理特征的关系，选取约60 m的剖面作为材料。沿剖面以1 m为间隔系统采集样品，测试粒度、水分含量、孔隙率、比表面积、有机质含量和土壤渗透性。分别使用地统计学方法和单分形理论和多重分形理论分析了物理性质和粒度分形特征的空间异质性。结果表明，土壤物理性质之间存在较强的空间相关性，但含水量受某些人为因素的影响。分形参数随深度的变化在其积累和发展时期受气候环境的影响。黄土堆积期，黄土层中粗颗粒含量增加，GSD浓度和对称性增加，使d ₁，d ₂和d ₁ / d ₀增加，d，α ₀，Δ α和Δ ˚F（α） 减少。土壤中细颗粒和粗颗粒的相对含量影响了GSD的分形特征和参数大小。奇异谱参数的增加表现为土壤非均质性增加，导致比表面积增加。多重分形参数与含水量和有机质的相关性受地层深度和形成年龄的影响较大。GSD分形特征与土壤渗透性之间存在相互响应。增加d ₁，d ₂和d ₁ / d ₀表示强土壤渗透性; 的增加α ₀，Δ α和Δf ( α ) 反映土壤均匀度高，不利于渗流过程的发生。研究成果为黄土高原的工程建设和生态修复提供了案例研究和理论依据。