高放核废物地下储库回填缓冲材料气体运移规律及交界面渗透特性研究

Gas generation and migration in buffer and host rock of the high-level radioactive waste disposal in deep is a key geomehcanical issue to evaluate the feasibility and safety of the repository. This study focuses on the gas transports properties of the buffer material and interface between the buffer and the concrete. Suction control technique and low permeability measurement at constant temperature will be employed to investigate gas permeability properties of the compacted bentonite subjected to different hydro-mechancial loading. The bi-phase transports mechanisms will be further studied combining the microstructure investigation. The relationship between the gas permeability and the pressure, the saturation degree, the initial dry density will be quantified. The gas breakout test will be carried out to quantify the breakout gas pressure. Based on the experimental results, a gas transport in the compacted bentonite model will be proposed to study the gas-water-solid coupling mechanisms of the material. The proposal will also study the gas permeability of the interface between the bentonite and the concrete. Three different tests will be done to identify all the factors which affect the transport properties of the interface. A double-porosity model will be considered to take into account the matrix and the interface simultaneous. The proposed gas migration model and the interface transfer model will be implanted in the FEM program to model the gas migration in the buffer material and evaluate the safety of the radioactive nuclear water disposal. The proposal will not only provide the solid experimental data for the evaluation of the high-level radioactive waste disposal, but also enrich the theories concerning gas-water-solid coupling mechanisms of the buffer material.

气体生成及其在回填材料和围岩内运移问题是高放核废物地质处置长期安全性评估的关键科学问题之一。本项目拟利用研制的恒温低渗透三轴测量仪和吸力控制系统，开展不同压力、饱和度、初始干密度条件压实膨润土气体渗透特性研究，探索气—液两相流动规律，揭示压实膨润土气—液两相流动机理；开展饱和压实膨润土气体突破试验，深入研究压实膨润土气体运移规律，确定气体临界突破压力，提出气体运移模型，揭示压实膨润土气—液—固耦合机理及材料损伤破坏机理；开展压实膨润土与混凝土交界面渗透特性研究，分析交界面渗透特性及其影响因素，提出同时考虑交界面和回填材料/混凝土介质渗透特性的渗透模型；将提出的气体运移模型和交界面渗透模型植入有限元程序，进行模型验证，并对高放核废物地质处置封存后期回填缓冲材料的气体密闭性和安全性进行数值仿真和科学评估，本研究将为我国高放废物地下储存库安全和可行性分析提供可靠的试验数据和理论基础。

气体生成及其在回填缓冲材料和围岩内运移问题是高放核废物地质处置长期安全性评估的关键科学问题之一。本项目以高庙子压实膨润土为主要研究对象，利用研制的恒温低渗透三轴测量仪和吸力控制系统，开展不同压力、饱和度、初始干密度条件压实膨润土气体渗透特性研究，揭示了不同条件压实膨润土气体渗透演化规律，在此基础上，提出了考虑温度效应的高庙子膨润土气体运移模型，并研发了相应的数值模拟程序。结合我国高放废物处置库实际情况，进行了地下处置库多层屏障气体运移过程的数值仿真。本研究成果为我国高放废物地下储存库安全和可行性分析提供了可靠的试验数据和理论基础。