硫酸钠盐渍土击实特性与压实度评价试验研究

Experiment and evaluation of compaction characteristics of sodium sulfate saline soil

合理的压实度对减小硫酸盐渍土地基的盐胀和溶陷病害具有重要意义。为探讨硫酸盐渍土的击实特性、击实后的微结构特征以及合理的压实度评价方法,对不同试样制备条件下的硫酸盐渍土进行了击实试验和电镜扫描。结果表明,硫酸盐渍土的击实特性和击实后的微结构特征与土中硫酸钠的状态密切相关:硫酸钠溶液具有润滑性,其含量的增加能显著提高硫酸盐渍土的击实性能,击实后,试样的土团粒主要呈表面光滑的薄层状,土体为流纹状镶嵌结构;而十水硫酸钠具有支架作用,其含量的增加使硫酸盐渍土的击实性能大幅降低,击实后,试样的土团粒呈浑圆状、粒径很小,土体为网状架空结构。根据这一新认识,进一步分析了试样制备方法和闷料时间对硫酸盐渍土压实度的影响,并给出了相应的压实度评价建议。该研究成果可为硫酸盐渍土压实度的合理评价提供理论依据,对硫酸盐渍土地基的辗压施工工艺具有参考价值。

A proper degree of compactness is very important for reducing the dilatancy and collapsibility of sulfate saline soil foundation. To investigate the compaction characteristics, the microstructure characteristics of sodium sulfate saline soil with different preparation conditions were investigated using scanning electron microscope（SEM）. It is found that the compaction characteristics and microstructure characteristics of sodium sulfate saline soil after compaction are related to the state of sodium sulfate in soil. As sodium sulfate solution possesses lubrication, the compaction characteristic of sodium sulfate saline soil is significantly improved as salt content increases. After the soil is compacted, the soil aggregates are mostly thin layers with smooth surface, and the soil has a rhyotaxitic mosaic structure. However, sodium sulfate decahydrate acts like a scaffold in the soil, the increase of salt content reduces significantly the compaction characteristics of sodium sulfate saline soil. After compaction, the soil aggregates are tiny and round, and the soil has a net-like open structure. The effect of sample pretreatment method and curing time on the compactness of sodium sulfate saline soil are analyzed, and the evaluation method for the compactness is suggested.