膨润土-砂混合材料三向膨胀力试验研究

利用改进的三向胀缩仪研究了掺砂率、干密度对高庙子膨润土-砂混合型缓冲/回填材料膨胀特性的影响。试验结果表明:混合物的三向膨胀力与掺砂率和干密度均呈指数关系,随干密度增加而增加,随掺砂率增加而减小;混合物的竖向膨胀力始终大于水平向膨胀力,在试验研究的范围内,水平向膨胀力与竖向膨胀力的比值随干密度变化较小,其值稳定在0.8左右;水平向膨胀力与竖向膨胀力的比值随掺砂率增加大致呈线性降低;混合物的三向膨胀力发展呈两个阶段,初始阶段膨胀力发展迅速可达到最大膨胀力80%左右,第二阶段膨胀力发展缓慢。最后从晶体扩张理论和双电层理论分析了混合物的膨胀特性机理。

Three-dimensional Swelling Pressure Characteristic of Bentonite-Sand Mixtures

This paper presents an experimental and theoretical study of the impact of sand mix ratios and dry density of bentonite-sand mixtures on the swelling characteristics through a series of experiments conducted by improved three-dimensional swelling-shrinkage apparatus. The result shows that the three-dimensional swelling pressure is obviously connected with the sand mix ratios and the dry density. The three-dimensional swelling pressure increases exponentially with the dry density,and decreases exponentially with the sand mix ratios. The vertical swelling pressure is greater than the horizontal swelling pressure. In the range of experiment, the dry density has less impact on the ratio of horizontal and vertical swelling pressure, and its value is stable at around 0.8. The sand mix ratio has obvious impact on the ratio of horizontal and vertical swelling pressure. The three-dimensional swelling pressure develops in two stages. The swelling pressure develops rapidly and can run up to about 80% of the maximum swelling pressure in the first stage. The swelling pressure develops slowly in the second stage. Finally, this paper analyzed the characteristics of three-dimensional swelling pressure of bentonite-sand mixture according to crystal expansion theory and electric double layer theory.