考虑温度影响的高压实GMZ膨润土气体渗透性能及其理论模型

Compacted bentonite has been commonly recognized as the most suitable buffer/backfill materials for construction of deep geological repository for disposal of high level nuclear waste. This proposal aims at Gao Miaozi (GMZ) bentonite, which has been selected as possible buffer/backfill material for Chinese high-level nuclear waste disposal program. A cell will be manufactured for gas permeability test on confined (constant volume) bentonite specimens. Gas permeability tests will be conducted on specimens with different initial dry densities and water contents with temperature control and related gas permeability will be obtained. Microstructure tests will be done on specimens before and after gas permeability tests for investigation of microstructure and its differences after experiencing gas permeation. Based on these, model for gas permeability in compacted GMZ bentonite will be developed with consideration of the coupling effects of temperature-water (suction)-microstructure variation (hydration). The mechanism of gas permeation in densely compacted GMZ bentonite under coupling conditions will be explored. The results expected will be of great importance for investigation of gas permeability behavior of GMZ bentonite and enrich unsaturated soil mechanics.

高放射性废弃物深地质处置库建设过程中，高压实膨润土被认为是最合适的缓冲/回填材料。本项申请针对拟作为我国高放废物地质处置库缓冲/回填材料的高压实高庙子（GMZ）膨润土，通过对既有气体渗透试验装置的改造，实现恒体积条件下的气体渗透功能；开展温度控制条件下、不同初始密实度与含水量试样的气体渗透试验，获取温控条件下、不同含水量与初始密实度试样的气体渗透参数；借助微观实验手段，获取气体渗透实验前、后的膨润土试样的微观结构及其变化特征，据以分析气体渗透过程中GMZ膨润土的微观演化机理；在此基础上，建立考虑温度-水（吸力）-微观变形（水化）等耦合作用的、高压实GMZ膨润土的气体渗透模型，揭示耦合作用条件下、高压实GMZ膨润土的气体渗透机理，弥补目前我国缓冲材料研究领域的不足。预期成果对于我国高压实膨润土气体行为特性研究，以及丰富非饱和土力学理论均具有重要的理论与工程实践价值。