高压实膨润土-砂混合型缓冲材料的渗透性能研究

Research on Permeability of High Compacted Sand-bentonite Mixtures as Buffer Material

缓冲材料作为高放废物深地质处置中的最后一道人工屏障,它的水力学屏障作用直接影响到化学屏障作用的有效发挥及处置库的长期稳定性及安全性。采用自主研制的高压实黏土渗透实验装置,探讨了不同干密度和掺砂率条件下的膨润土-石英砂混合型缓冲饱和侧限渗透性能。实验研究结果表明,随着掺砂率的增加,膨润土-石英砂混合型缓冲材料的渗透系数先减小再增大,当掺砂率为10%时,缓冲材料的渗透系数最小,其最佳掺砂率为10%;缓冲材料的渗透系数随着试样干密度增加而减小,干密度控制在1.6~1.8 g/cm^3时,能够更好地满足高放废物深地质处置库对缓冲材料的渗透特性的要求。

Buffer material as the last artificial barrier in the deep geological disposal of high-level radioactive waste,its hydraulic barrier function works effectively or ineffectively directly influence the chemical barrier function,the long-term stability and security of the repository. Self-developed high-pressure clay rigid wall permeameter was used to explore saturated permeability performance of bentonite-quartz sand mixtures as buffer material in different dry density and mixed sand ratio. The test results show that with sand mixing ratio increase permeability coefficient showed a trend of first increase and then decrease,10% sanding rate permeability coefficient is minimum,shows that the best sanding rate is 10%; permeability coefficient decreases with the increase of dry density. When maintain dry density between 1. 6 g/cm3 to 1. 8 g/cm3,the permeability coefficient can be better meeting the request about buffer material in the repository of high-radioactive waste disposal.