压缩变形影响下的土-水特征曲线及其简化表征方法

非饱和土的本构关系研究需获得任意压缩变形条件下的土-水特征曲线,但试验测量往往只能给出特定状态下的土-水特征曲线。压缩变形改变土体孔隙分布特性,从而影响其土-水特征曲线。采用压汞技术、核磁共振技术、扫描电镜研究压缩变形条件下土体孔隙孔径分布的变化规律,基于实测及已有试验数据研究土-水特征曲线变化规律,通过孔径分布变化规律阐释压缩变形影响土-水特征曲线的机制。研究结果表明：在不同的压缩变形条件下,土体（单位颗粒质量）的累计孔隙体积分布整体上呈现“扫帚型”分布,质量含水量表示的土-水特征曲线也呈现相似的分布,二者变化规律较为一致,从而揭示了土-水特征曲线随压缩变形变化的内在机理。在此基础上,建议了一种压缩变形影响下的土-水特征曲线简化表征方法,其描述的土-水特征曲线与试验结果吻合较好。

Influence of compression deformation on the soil-water characteristic curve and its simplified representation method

The soil-water characteristic curve (SWCC) under random compression deformation is needed for study on constitutive relations of unsaturated soil, while experiments only give the SWCC under a specific condition. Compression deformation influences SWCC by way of influencing the pore distribution property. Firstly, the variation law of pore-size distributions with compression deformation was studied by using the mercury injection technique, nuclear magnetic resonance and the scanning electron microscope. Then, the variation law of SWCC with compression deformation was systematically studied based on experimental results and available published data. The results show that, for the pores corresponding with the unit particle mass, the cumulative volume or area distributions of different compression deformation present as a "broom" profile, while the SWCCs in terms of mass water content of different compression deformation present as a similar profile. The good agreement of the variation laws of pore-size distributions and SWCCs shows that the internal variation mechanism of SWCC with compression deformation can be explained through pore-size distributions. Also, a simplified representation method was presented to describe the influence law of compression deformation on SWCC, and its rationality was testified by experimental results.