通过试验研究了试样静置时间对不同干密度和含水率压实高庙子膨润土抗拉强度的影响. 在保持干密度和含水率不变的条件下, 将不同初始状态试样分别静置 0, 7, 15, 30, 90 d, 利用巴西试验测其抗拉强度, 并结合压汞试验进行分析. 试验结果表明: 随静置时间的增加压实高庙子膨润土的抗拉强度前期减小较多, 后期逐渐趋于稳定; 在同一含水率下, 静置时间对膨润土抗拉强度的影响程度随干密度的增大而减小. 静置时间对膨润土抗拉强度的影响如下: 在静置过程中, 由于土中水分子逐渐向蒙脱石层间移动, 蒙脱石晶层吸水逐渐展开、水化, 故颗粒间连接变弱, 使抗拉强度降低. 该成果为核废料处置库膨润土砌块的存放和在安装过程中其抗拉强度的变化范围提供参考数据.

In this study, the effect of ageing on the tensile strength of compacted Gaomiaozi bentonite was investigated under different dry densities and water contents. The dry densities and water contents were maintained constant during curing periods of 0, 7, 15, 30 and 90 days, respectively. The tensile strength was measured using Brazilian tests and the specimens were analyzed through mercury intrusion porosimetry tests. The test results indicate that the tensile strength of Gaomiaozi bentonite decreases significantly in the early stage and tends to stabilize gradually in the later stage with ageing time. At the same water content, the effect of ageing on the tensile strength of the bentonite becomes less significant with the increase in dry density. The effect of ageing on the tensile strength is due to the gradual movement of the water molecules in the soil to the smectite interlayer during the curing periods and the subsequent gradual development of the smectite inter-lamellar water absorption. This process weakens the connection, decreasing the tensile strength. Smectite hydration results in the decrease in the number of macropores and the gradual increase in the number of small pores among the aggregates. Thus, the findings of this study provide a reference for the range of tensile strength of a bentonite block in a nuclear waste repository during storage and placement.