膨润土-砂混合型缓冲/回填材料土-水特征曲线研究

高放废物（HLW）深地质处置中，在膨润土中添加一定比例的石英砂能优化缓冲/回填材料的性能。利用水汽平衡法，对高庙子压实膨润土-砂混合物在不同温度、掺砂率和干密度条件下的土-水特征曲线（SWCCs）进行试验研究，分析温度、掺砂率与干密度对混合物土-水特征曲线的影响。试验结果表明，随着温度升高，混合物的持水能力明显下降；在试验控制吸力范围内，低吸力段掺砂率对土-水特征曲线影响明显，高吸力段掺砂率对混合物土-水特征曲线的影响逐渐降低；干密度对混合物的土-水特征曲线基本没有影响。根据试验数据建立了不同温度和掺砂率条件下膨润土-砂缓冲/回填材料土-水特征曲线的经验公式，可用来预测不同温度和掺砂率条件下的膨润土-砂混合型缓冲/回填材料土-水特征曲线

Test on soil-water characteristic curves of bentonite-sand mixtures

In the geological disposal of high-level radioactive waste (HLW), the performance of the cushioning material will improve when the bentonite is mixed with a certain proportion of quartz sand. A research on soil-water characteristic curves of compacted mixture of bentonite-sand for higher suctions is carried out through moisture balance method; and influences of temperature, sanding rate and dry density on water retention capacity of the bentonite-sand mixture are analyzed. The results show that the water retention capacity of the mixture decreases obviously with temperature increase. Within the controlled suction range, the influence of sand mixing ratio on the soil-water characteristic curve is evident when suction is low; Within the controlled suction range, the influence of sanding rate on the soil-water characteristic curve is evident when suction is low, and at high suction the effects gradually decreased. On the other hand, dry density almost has no effect on the soil-water characteristic curve. Empirical formulas for SWCCs of bentonite-sand mixed buffer/backfill material under conditions of different temperatures and sanding mixing ratio are proposed by fitting the experimental data; and SWCCs of this material with different temperatures can be thus predicted.