长春地区季冻土微观结构特征的定量评价

Quantitative assessment of micro-structure feature of seasonal frozen soil in Changchun area

利用计算机图像处理系统对长春地区季冻土的SEM图像进行分析,结合分形理论,对土的微观结构、结构单元体的大小、形状、分布以及定向性进行定量评价,以分析土结构对水分迁移机理的影响。通过研究表明:长春地区季冻土颗粒直径主要在2-10μm,粉粘粒成分含量比较多,具有团聚状结构,定向性单一,大小胶结体同时存在,孔隙多为毛细孔隙,比较密集,规则,畅通,直径主要为<2μm,有利于水分储存和形成迁移通道;颗粒分布分维值多在1.1-1.2之间,孔隙定向分维值为0.79-0.95。降低颗粒分布分维数,增加孔隙定向分维数,能有效防止水分迁移和冻胀作用。

The SEM images of seasonal soil in Changchun were analyzed by applying computer image pro- cessing system. The micro-structure, structure element size, shape, distribution and directing property of seasonal soil were assessed quantitatively associating with fractal theory in order to analysis soil structure influence to water translocation. The results showed that the particle diameter of seasonal frozen soil in Chang-Chun area is from 2- 10μm, in which includes more silty clay content, particle has aggregate struc-ture, single directing property, little and large cement coexist. Pore in soil is capillary porosity which is close packing, and regular, expedite, diameter is less than 2μm, which is propitious to water storage and supplies water translocation path. Soil particle distribution fractal dimension is 1.1 - 1.2 and pore direction fractal dimension is 0.79 - 0.95. Particle distribution dimension changes with different depth in different road while pore direction is less. Declining particle fractal dimension and increasing pore direction fractal dimension can prefect water translocation and frozen heaving effect.