干化-湿化路径下红黏土微观结构演化规律研究

Microstructural changes in red clay on drying-wetting paths

以桂林红黏土为研究对象,借助扫描电子显微镜法(SEM)和压汞法(MIP)对不同初始孔隙比的压实土样和泥浆土样在干化-湿化路径下微观结构演化规律开展研究.扫描电子显微镜结果表明,饱和压实土样的微观结构主要由集聚体、集聚体间大孔隙和集聚体内小孔隙(颗粒间孔隙)组成;饱和泥浆土样的微观结构主要由片层状的黏土颗粒和较为均匀的颗粒间孔隙构成.压汞试验结果表明,压实土样和泥浆土样的孔径分布曲线(PSD)在干化-湿化路径下分别呈现双峰和单峰分布特征;干化-湿化路径下压实土样主要是集聚体间大孔隙的变化,泥浆土样仅需要考虑颗粒间孔隙的变化;与压实土样相比,初始孔隙比对泥浆土样的孔隙变化影响很小.

Taking Guilin red clay as the research object, scanning electron microscopy(SEM) and mercury intrusion porosimetry(MIP) tests were conducted to study the microstructural evolution laws of compacted and reconstituted soils with different initial void ratios on drying-wetting paths. The SEM results show that the microstructure of the saturated compacted soils mainly comprises aggregates,interaggregate pores, and intraaggregate pores(interparticle pores). The microstructure of the saturated reconstituted soils mainly comprises layered clay particles and relatively uniform interparticle pores. The MIP results show that the pore size distribution curves of the compacted and reconstituted soils exhibit a bimodal and a unimodal distribution, respectively. On the drying-wetting paths, the changes in the interaggregate pores are the main factor for the compacted soils, while the changes in the interparticle pores are the only factor for the reconstituted soils. Compared with the compacted soils, the initial void ratio has less effect on the pore change of the reconstituted soils.