Na-K-Ca盐梯度循环作用下高压实GMZ膨润土水－力学性能衰变机理研究

项目名称： Na-K-Ca盐梯度循环作用下高压实GMZ膨润土水－力学性能衰变机理研究

项目编号： No.41272287

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 天文学、地球科学

项目作者： 陈永贵

作者单位： 同济大学

项目金额： 85万元

中文摘要： 针对处置库近场化学环境对缓冲/回填材料长期性能的影响，以北山预选处置库场地和高庙子(GMZ)膨润土为研究背景，通过系统试验和数值分析，探索高压实GMZ膨润土在近场循环化学作用下水－力学性能衰变机理，建立工程屏障系统长期安全性评估方法。基于非饱和多相吸力控制技术，改造恒体积高压膨胀－渗透仪，开展Na-K-Ca盐梯度循环下的膨胀力、固结、有限变形和渗透性等试验，全面揭示膨润土水-力学性能衰变规律；利用压汞法和环境扫描电镜，观察膨润土水化过程中的微观结构变化，定量研究化学效应引起性能衰变的微观机制；借助X衍射、能谱分析和化学测试，查明试验中膨润土矿物相态和化学成分转变，深入阐明膨润土水-力学性能衰变的化学机理；由此建立基于化学-力学-渗流耦合效应的性能损伤本构模型，采用先进数值方法模拟膨润土水-力学性能衰变过程，评价工程屏障系统长期安全性。预期成果将为我国工程屏障系统建设提供理论依据和技术支持。

中文关键词： 深地质处置；高压实膨润土；化学循环；水-力学性能；演化机理

英文摘要： Highly saline solution are expected to play an important role in long term safety assessment of engineering barrier system (EBS) for storage of high level radioactive waste (HLW). In China, the Gaomiaozi (GMZ) bentonite has been selected as the first choice of buffer/backfill material and the Beishan area in Gansu Province has been considered as the most potential repository site for HLW disposal. In this study, laboratory tests and numerical simulations will be performed to investigate the effects of chemical cycles near the repository site on the hydro-mechanical (HM) behavior of compacted GMZ bentonite, and then to evaluate the long term performance of EBS. Firstly, based on the multi-phase suction controlling technique for unsaturated soil, a constant-volume cell for high-pressure swelling-infiltrate test will be improved to produce a Na-K-Ca salinity gradient cycling for chemical test. Then, laboratory tests like swelling, confined deformation, 1D consolidation and infiltrate tests will be conducted to study the HM behavior of compacted GMZ bentonite. Secondly, in order to research the effects of chemical cycles on HM properties due to microstructure changes, the mercury intrusion porosimetry (MIP) and environmental scan electronic microscope (ESEM) will be applied to quantify the microstructure characteris

英文关键词： Deep geological disposal；Copmacted bentonite；Chemical cycles；Hydro-mechanical behavior；Evolution mechanism