膨润土加砂混合物膨胀特征试验研究

运用自行研制的膨胀仪对膨润土加砂混合物进行了一系列膨胀力及膨胀应变等膨胀特性的试验研究，分析了膨胀力随时间的变化规律、两向膨胀力之间的关系和膨胀应变与时间及吸水量之间的关系。试验研究表明，膨润土加砂混合物的最大膨胀力以及最大膨胀应变主要取决于混合物的最初干密度和膨润土含量，并且随着二者的增大而增大；膨润土加砂混合物的水平膨胀力与竖向膨胀力之比随着混合物干密度的增大减小，并且与干密度近似成线性关系；不同膨润土含量的膨润土加砂混合物的膨胀应变与时间成双曲线关系，与吸水量近似呈S型曲线关系，并且其最大膨胀应变与膨润土含量存在指数关系。试验结果对高放废物深处置库中的缓冲回填材料设计具有一定的参考价值。

Experimental study of swelling characteristics of bentonite-sand mixture

A series of experimental researches of swelling pressure and swelling strain of bentonite-sand mixture are conducted by using self-developed swelling apparatus.Based on the experimental data obtained,the relationships between swelling pressure and time,vertical and horizontal swelling pressures,swelling strain and time,and swelling strain and water-absorbing volume are analyzed.The results show that the maximum swelling pressure and the maximum swelling strain of bentonite-sand mixture depend on the initial dry density and bentonite content of mixture,and increase with the increasing of these two factors.The increase of the dry density results in the decrease of the ratio of horizontal and vertical swelling pressures,and a linear relationship can be obtained between them.For bentonite-sand mixture with different bentonite contents,a hyperbolic relationship is obtained between swelling strain and time,and an approximate S-curve relationship is obtained between swelling strain and water-absorbing volume.Furthermore,the maximum swelling strain and bentonite content of bentonite-sand mixture demonstrate an exponential relationship.The experimental results are of reference value for design of buffer and back-filling materials in high-level radioactive repositories.