高压实新疆阿尔泰膨润土微观结构随吸力变化特征

Change of the Microstructure of High Compacted Bentonite in Altay of Xinjiang with Suction

采用压汞法(MIP)和扫描电镜(SEM)法,在自由和侧限状态下,试验研究了高压实新疆阿尔泰膨润土在不同吸力条件下的微观结构变化特征。吸力的控制采用了气相法和渗析(液相)法。研究结果表明:(1)低吸力范围内,自由膨胀和侧限条件下的高压实膨润土土水特征存在明显差异;(2)膨润土在自由和侧限状态下的水化过程中呈现出了截然不同的微结构变化特征。自由膨胀条件下,土的吸水膨胀量主要来自土中大孔隙的逐渐膨胀。侧限状态下,随着控制吸力的降低,膨润土的大孔隙逐渐被压缩,较小孔隙的数量不断增加,土中孔隙分布变得更加均匀。

The microstructure changing characteristics of high compacted bentonite in Altay, Xinjian with different suctions were studied at unconfined and laterally restrained conditions by using mercury intrusion porosimetry （MIP） and scanning electronic microscope （SEM） technologies. The vapor phase method and osmotic technique were used for suction controlling. The results showed that （ 1 ） in low suction range, the soil-water features of bentonite had significant differences at the conditions of confined and unconfined; （2） The microstructures of bentonite changed differently during the process of hydrationat the conditions of confined and unconfined. At the unconfined conditions, the bentonite swelling came from gradual swelling of the big pores. While at confined conditions, with the decrease of the control suction, the big pores were compacted and the number of smaller pores increased, resulting in distribution of pores becomes more uniform.