高压实高庙子膨润土研究进展

高放废物深地质处置中,缓冲/回填材料系统起着工程屏障、水力学屏障、化学屏障,以及传导和散失放射性废物衰变热等重要作用,是高放废物地质处置库长期安全性和稳定性的有效保障。前人研究表明,膨润土是理想的缓冲/回填材料。本文在归纳总结压实膨润土相关室内试验研究成果的基础上,采用水汽平衡法和渗析法吸力控制技术,借助恒体积膨胀法等试验手段,试验研究了自由膨胀与侧限两种条件下,高压实高庙子膨润土的土水特征及膨胀力发展规律。结果表明,低吸力范围内,高压实高庙子膨润土在自由膨胀和侧限条件下的土水特征存在明显差异。膨胀力随时间的变化曲线是一条渐近线,而时间/膨胀力与时间之间存在很好的线性关系;膨胀力和干密度之间存在指数关系,干密度是影响膨胀力的一项重要的外部因素。

ADVANCES STUDY OF DENSELY COMPACTED GAOMIAOZI BENTONITE FOR USING AS BACKFILL MATERIALS

In the deep geologicalrepositoryfor the disposalof high radioactive nuclearwaste, buffer/back-fill material system works as engineering barrier, hydraulic barrier, chemical barrier and transmissionof heat generated by nuclear waste, which is an efficient guaranteefor the long-term safety and stabilityof the repository. Historicalresults show that bentonite is an ideal buffer/back-fill material. Based on a review of lab tests results of bentonite, the characteristics of water retention and expansive pressure of Gaomiaozi bentonite, which has been chosen as the first choice for using as buffer/back-fill materials in deep disposal of high radioactive waste in China, has been tested and analyzed under unconfined and confined conditions by using osmotic and vapourphase techniques. Results show that, for lower suction, there is a clear difference in water retention properties of densely compacted Gaomiaozi bentonite between confined and unconfined conditions. For the Gaomaiozi Bentonite tested here, there is an exponential relationship between swelling pressure and dry density, and dry density is an important external factor to swelling pressure. All results obtained here are very important to the study of the swelling property of Gaomiaozi bentonite.