本项目结合我国高放废物地质处置研发的实际工程需求，以我国处置库首选缓冲/回填材料高庙子膨润土为对象，拟对其在热、水、力共同作用下的宏微观行为开展系统的试验与理论研究。在宏观试验方面，利用自主研发的系列膨润土高温试验设备，开展不同温度下的膨胀、非饱和固结、持水、非饱和渗水/渗气等试验；在微观试验方面，以压汞分析与环境扫描电镜为手段，研究宏、微观孔隙在不同热-水-力作用路径下的变化规律。根据宏微观试验结果，建立热-水-力共同作用下微观孔隙演化模型；基于所建立的微观演化模型，构建考虑微观结构变化的非饱和持水、渗透及变形本构方程，并将其融入申请人已建立的热-水-力多场耦合数值模型及程序加以应用。本项目研究成果不仅可分析非饱和膨润土微观结构变化引起的复杂宏观行为，并且能用于预测实际地质库热-水-力耦合条件下非饱和膨润土中的微观结构变化，有助于深化对膨润土在处置库中的实际工作性能与安全状态的认识。

This project focuses on the macroscopic and microscopic thermo-hydro-mechanical behaviour of GMZ bentonite, which has been selected as the candidate Chinese buffer/backfill material of the geological repository of HLW. A series of macroscopic tests, including swelling tests, water retention tests, suction-controlled oedometer tests, unsaturated permeability tests, etc., will be conducted at different temperatures using several self-developed apparatus, which has been specially designed for bentonite tests and has the capacity of the application in high temperature. Microstructure evolution in the above macroscopic tests will be investigated systematically and quantitatively using mercury intrusion porosimetry (MIP) and environmental scanning electron microscopy (ESEM). Based on test results, a microstructure model will be proposed to describe the microporosity evolution with suction, stress and temperature. Utilizing the microstructure model, a series of microstructurally based hydraulic and mechanical constitutive models will be developed based on existing and well-evaluated macroscopic models, and will be incorporated into the finite element code developed previously by the applicant for the coupled thermo-hydro-mechanical analysis of unsaturated soil. The research results of this project can be utilized not noly to analyse the complex macroscopic behaviour of unsaturated bentonite using quantitative information of microstructure alteration, but also to predict the microstructure state of bentonite in the real geological repository condition. It is expected that understanding of buffer/backfill material will improved in both macroscopic and microscopic sense through this project.