不同压实成型条件下非饱和黄土的持水与渗水特性

    Study on water-retention and permeability characteristics of unsaturated loess under different compaction conditions

    • 摘要: 为探究不同成型过程对非饱和黄土持水与渗水特性的影响,采用压力板仪对3种不同初始干密度的常规重塑(层状压实)、横观各向同性(K0应力状态)及各向同性(各向等压状态)重塑黄土试样,进行不同竖向应力的土水特性曲线试验。研究结果表明,三种黄土试样的持水能力与渗透性演变存在系统性差异:常规重塑黄土SWCC随竖向应力的增大向下移动,持水能力减弱;横观各向同性黄土SWCC在吸力50~100 kPa范围内出现交叉现象,交点后曲线斜率随竖向应力增大而减小,其持水能力增强;各向同性黄土随着干密度的增大,其SWCC下降阶段的变化规律趋近于横观各向同性黄土;不同竖向应力下各向同性试样渗水特性对竖向应力的敏感度最高,常规重塑试样次之,横观各向同性试样敏感度最低。研究成果可为相关工程应用提供有益参考。

       

      Abstract: In order to explore the influence of different forming processes on the water-retention and seepage characteristics of unsaturated loess, the pressure plate apparatus is used to test the soil-water characteristic curves of three types of remolded loess specimens with different initial dry densities, including conventional remolded (layered compaction), transversely isotropic (K0 stress state) and isotropic (isotropic stress state) conditions. The results show that there are systematic differences in the evolution of water-retention capacity and permeability of the three loess specimens: the SWCC of conventional remolded loess shifts downward with the increase of vertical stress, and the water holding capacity decreases; the SWCC of transversely isotropic loess exhibits an intersection phenomenon in the range of 50~100 kPa suction. After the intersection point, the slope of the curve decreases with the increase of vertical stress, and its water holding capacity increases. With the increase of dry density, the variation law of SWCC decline stage of isotropic loess approaches that of transversely isotropic loess. Under different vertical stresses, the sensitivity of permeability characteristics of isotropic samples to vertical stress is the highest, followed by conventional remolded samples, and the sensitivity of transverse isotropic samples is the lowest. The research results can provide useful references for related engineering applications.

       

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