粒径尺寸对红黏土持水曲线及孔径分布影响研究

Effect of Aggregate Size on Water Retention Curve and Pore Size Distribution of Lateritic Clay

为探究粒径尺寸对红黏土的持水特性及孔径分布的影响,用轴平移技术和蒸汽平衡技术对不同粒径尺寸制备的红黏土压实样开展广吸力范围内的持水特性试验和压汞试验,基于不同粒径尺寸试样的持水曲线和孔径分布曲线,揭示粒径尺寸影响土体持水特性的细观机理。具体结论如下:(1)粒径尺寸只对压实样在低吸力范围的持水曲线产生影响,表现为粒径尺寸越小,制备试样进气值则越大。(2)不同粒径制备的饱和压实样均为单峰型孔径结构,且粒径尺寸越小,制备试样的集中孔径分布的峰值越高,分布的范围也越小,表明粒径越小的试样的孔径分布越均匀。(3)预测和实测持水曲线的比较结果显示,由于无法考虑土体干化路径下的孔隙比减小,孔径分布曲线可用于预测土体在对应吸力下的含水率,而预测饱和度低于实测的饱和度。

To investigate the effect of aggregate size on water retention characteristics and pore size distributions(PSDs),the water retention curves measurement and mercury intrusion porosimetry(MIP)over a wide suction range,were conducted on lateritic clay specimens with different aggregate sizes by axial translation techniques(ATT)and vapor equilibrium techniques(VET).The water retention and PSD curves were obtained to explore the microscopic mechanism by which aggregate size affects water retention in soil.The results showed that aggregate size only had great effect on the water retention in the low suction range,and the air-entry value was higher for specimen with smaller aggregate size,and the smaller the aggregate size dimension,the larger the inlet value of the specimen.The PSDs were unimodal for saturated compacted specimens with different aggregate sizes.It was found that the smaller aggregate size of the specimen,the higher the peak of the concentrated PSD,and the narrower the distribution range,which means the smaller the particle size,the more uniform the pore size distribution.The comparison of predicted and measured water retention curves proved that due to the neglection on the reduction of void ratio of specimen in drying process,the PSD curve could predict be used to predict the water content with different suctions,while the predict saturation was lower than the measured result.