土-水特征曲线测量过程中孔隙分布的演化规律探讨

Evolution law of pore-size distribution in soil-water retention test

测量了在宽广吸力范围内原状样和压实样的脱湿持水曲线,对比分析了单双峰结构持水性能的差异;并利用压汞试验测试两种土样在脱湿过程的孔隙分布,分析了两者的差异并探讨了脱湿过程孔隙的演化规律;在考虑收缩变形的基础上,基于孔隙分布曲线确定了土-水特征曲线的基本参数。试验结果表明:原状样在宽广吸力范围内基本上呈单峰孔隙结构;饱和压实样具有单峰孔隙结构,随着吸力的增加,双峰结构越来越明显,当吸力达到很大时,演化成完全双峰孔隙结构。原状样的持水曲线为经典的S形,而压实样的持水曲线在过渡段出现了水平台阶状;低吸力段,压实样的持水曲线低于原状样,而高吸力段,两者的持水曲线基本重合。基于孔隙分布曲线确定了控制持水曲线进气值和残余值的孔径,并计算出对应的吸力值,其值更符合实际物理意义。

This paper is to measure the soil-water retention curves(SWRC)of undisturbed and compacted soil specimens and compare the differences in measured data between these two soils.The mercury intrusion porosimetry(MIP)tests are conducted to explore the difference in the pore size distributions(PSD)between the undisturbed and compacted specimens and investigate the evolution law of PSD during drying.By considering shrinkage during drying,the basic parameters of SWRC can be determined based on the PSD.The results show that the undisturbed specimens in the wide suction range exhibit a unimodal PSD.The saturated compacted-specimen exhibits a unimodal PSD,but becomes the bimodal structure obviously during further drying.The SWRC of undisturbed specimens has a typical shape of"S",but the compacted specimens have a"horizontal stage"in the transition zone.The pore diameters governing the air entry value and residual value can be determined by the PSD of MIP tests,and then corresponding suctions can be calculated,which are consistent with the physical meaning.