混合型缓冲回填材料膨胀变形试验研究

Experimental study of swelling deformation for compacted bentonite-sand mixture as buffer material

选用高庙子钠基膨润土(GMZ001)为缓冲回填材料的主料,添加不同比例的石英砂,对掺砂率分别为0%、10%、20%、30%、40%和50%的膨润土-砂混合物压实试样进行室内膨胀变形试验。结果表明:膨胀率随时间呈指数增长;掺砂率一定时,最大膨胀率随初始干密度的增大而线性增长;初始干密度一定时,最大膨胀率与掺砂率呈二次函数关系。引入有效黏土密度的概念对最大膨胀率进行计算,建立了任意掺砂率和初始干密度条件下膨润土-砂混合物最大膨胀率归一化模型,为混合型缓冲回填材料在高放废物地质处置中膨胀行为的预测与控制提供了依据。

GMZ001 bentonite is chosen as the main buffer material in high level radioactive waste（HLW） geological disposal.Laboratory swelling test was conducted on compacted mixture of GMZ001 bentonite and quartz sand in different addition of 0,10%,20%,30%,40% and 50%.Test results show that the swelling strain of the mixture is exponentially increased with lapse of time.The maximal swelling strain shows a linear increase with initial dry density;while it increases with sand addition presents a parabola.By the use of the concept bentonite filled density,an optimum model has been established to describe the relationship between maximal swelling strain with sand addition percentage and initial dry density,which provides a useful tool for predicting and controlling the swelling behavior of bentonite-sand mixture in HLW geology disposal.