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针对当前黄土地区公路自然区划宏观程度高、实际难应用等问题,研究新的区划方案、寻找理想的区划指标意义重大。以分形理论为基础,分析了甘肃黄土粒度分布的分形结构特征。结果显示,黄土具有良好的统计自相似性,其分维值介于2.15~2.705之间;黄土的粒度分维值可定量表征黄土的物理、力学和水理性质及差异,即黄土的粒度分维值越大,其干密度、比表面积、粘聚力、内摩擦角越大,微、小孔隙含量越高,但其平均孔径、孔隙比、湿陷系数和渗透系数越小,其工程地质性质愈稳定;在空间上,黄土粒度分维值存在显著的区域性变化规律,反映了甘肃黄土地区二级公路自然区划的5个二级区的差异。认为黄土粒度分维值可作为公路自然区划的主要指标之一,参与三级区的划分,为公路工程的设计、施工提供科学依据。
In view of the current macroscopic high degree of highway natural division in the loess area and the practical difficulties in application and so on, it is of great significance to study the new division plan and find the ideal division index. Based on the fractal theory, the fractal structure of the loess particle size distribution in Gansu Province was analyzed. The results show that the loess has a good statistical self-similarity and the fractal dimension value is between 2.15 and 2.705. The fractal dimension value of loess can quantitatively characterize the physical, mechanical and hydraulic properties and differences of loess, ie, the particle size distribution of loess The larger the value of the dimension is, the higher the dry density, specific surface area, cohesion and internal friction angle are, and the higher the content of micropores and pores is, the smaller the average pore size, porosity ratio, collapsibility coefficient and permeability coefficient are. The more stable the nature, the spatial distribution of fractal dimension of loess has significant regional variation, which reflects the differences of five second-level zones in the natural division of the second-level highway in loess region of Gansu Province. It is considered that the fractal dimension of loess particle size can be regarded as one of the main indexes of natural division of highway and participate in the division of tertiary area, which can provide scientific basis for the design and construction of highway engineering.