不同温度下膨润土膨胀变形行为研究

Study on Bentonite's Swelling Strain Behaviour at Different Temperatures

以压实膨润土试样为对象,进行了不同温度与竖向荷载下的膨胀变形试验,并在膨胀变形试验结束之后开展了压汞试验,研究了温度、竖向荷载对其膨胀变形行为及微观孔隙结构的影响。试验结果表明:温度越高,最终膨胀率越小,不同温度下,最终膨胀率均与竖向荷载成对数关系;温度越高,膨胀稳定时间越短,但温度对膨胀速率的影响在不同竖向荷载下存在差异。从微观方面看,压实膨润土试样的孔径分布在吸水膨胀前后均呈"双峰"模式;试样吸水后,集合体内的小孔膨胀致使原有集合体崩解,集合体内的小孔减少,而集合体间的大孔增多。温度和竖向荷载越大,大孔孔径及孔径密度越小,但基本不影响小孔的孔径分布。

Consolidation tests at different temperatures and vertical loads and MIP tests were carried out on compacted samples of sodium bentonite to investigate the influence of temperature on bentonite’s swelling strain.Results indicates that:the swelling strain decreases with the increase of temperature;at different temperatures,the final swelling strain has exponential relationship with vertical loads;the swelling duration decreases with the increase of temperature,while the influence of temperature on the swell?ing rate is different under vertical loads.In the microscopic aspect,the pore size distribution of compacted bentonite samples shows a“doublepeak”structure before and after soaking.After soaked,micropores swell and cause aggregation collapse,micropores decrease and macropores increase.The size and density of macropores decrease with increase of temperature and vertical load,while temperature and vertical load have no influence on the pore size distribution of micropores.