非饱和黄土宏细观含水状态与结构性的研究

摘要

土水特征曲线可以反映土中孔隙的空间分布与变化情况,利用土体的孔隙分布特征可以研究非饱和土的持水特性和结构特性.首先通过室内压力膜仪试验,研究了非饱和黄土的土水特征曲线的进气压力值 、脱湿速率 、孔径分布参数等指标与干密度 、击实含水率的关系;然后基于孔径分布计算理论和试验结果,给出了非饱和黄土的孔径分布曲线,用来评价土体内部孔径的分布情况,分析了非饱和黄土干密度和击实含水率对土的宏细观含水状态和结构性的影响机理.结果表明:增大非饱和土的干密度,可使孔径变小,孔隙结构分布范围变窄,土颗粒从架状结构向致密结构转换,基质吸力变化引起含水率变化较小,持水特性提高,土体的脱湿速率变慢,进气值呈现增大趋势;而击实含水率位于最优含水率湿测时,影响并不明显.%SWCC can reflect structural property and void distribution of soil.Pressure plate extractor tests considering dry density and compaction water content were carried out and the influences of the two factors on soil-water characteristic curve were analyzed.The relations of retention parameters α,n and residual water content θr with dry density and com-paction water content were analyzed.According to the pore distribution theory and experimental data,pore distribution curve of loess was obtained.Through the microstructure analysis,the relationship between pore distribution of loess and moisture condition was established.The results show that when dry density increase,pore distribution tends to compact and the changes of water content become slight with change of matric suction,so the water retention capacity improves.When the compaction water content is larger than optimum water content,the effect mentioned above is very slight,thus the compaction water content being close to optimum water content is suggested.