非饱和粘土岩损伤和渗透演化规律研究

In order to reasonably estimate and evaluate the stability and the safety of underground structures in deep clayey formation, such as oil or natural gas storage caverns and radioactive nuclear waste repository, it needs a better understanding on the damage behavior and self-sealing capacity of argillaceous rocks subjected to coupled hydromechanical loads and their corresponding mechanisms，which is an important issue in geomechanics. In this study,a series of desaturation and resaturation tests will be carried out at various stress levels in a uniaxial compression system with an optiical observation setup and in an environmental scanning electron microscope.The deformation and the damage of the materialat various scales (10 μm - cm) will be identified by means of digital image correlation (DIC) technique and the relationship between the damage and suction, water content, microstructure will be quantified.The mechanical behavior (modulus, rupture mode, plastical deformation) of unsaturated argillaceous rocks will be identified by carrying outa series of uniaxial and triaxial compression tests.In order to study the self-sealing of damaged argillaceous rocks，the fractured argillaceous rocks will be saturate under controlled stress-pore pressure conditions. The permeability measurements will be also carried out during the test to quantify the self-sealing capacity of the studied material.This projet should be a foundamental research on the damage and the self-sealing behavior of argillaceous rocks.

粘土岩损伤和渗透演化规律是能源、核废料泥岩储库长期稳定性、安全性评估等科学研究的重要内容之一。项目将利用改进的单轴干湿循环光学测量系统和环境电子扫描电镜内干湿循环系统，开展粘土岩不同应力水平干湿循环试验，研究粘土岩不同尺度（10 μm - cm）变形和损伤特征，以及它们与应力、湿度梯度、含水量及材料细观结构和组成之间的关系。通过单轴和三轴不同应力路径加卸载试验，研究非饱和粘土岩力学特性（弹塑性，强度）与含水量之间的关系。根据试验分析结果，提出非饱和粘土岩损伤演化模型。应用不同应力-渗流耦合条件下损伤粘土岩饱和试验，研究损伤粘土岩裂隙面自愈机理，并利用低渗透测量系统，研究粘土岩损伤自愈过程渗透演化规律。项目研究成果将丰富粘土岩损伤和自愈机理试验和理论研究。

粘土岩由于具有低渗、力学稳定、强吸附等物理特性，被许多国家认为是一种理想的高放核废物地质处置地层，而它的损伤及演化规律是高放核废物地质处置库长期安全稳定性分析的重要内容之一。本项目针对一种粘土岩-高放核废物地质处置地层，开展了非饱和干湿循环试验，获得了其土水特征曲线；并利用细观原位测试技术，定量分析了干湿循环对粘土岩变形和结构的影响，发现了干湿变形的非线性、各向异性、不可逆性，揭示了变形损伤机理；完善了低渗透测量系统，确定了不同饱和状态渗透率演化规律，最后确定出渗透率与损伤演化之间内在联系。相关研究成果总发表SCI，EI论文10余篇，获得发明专利4项，获得省部级一等项1项，研究工作为我国高放核废物地质处置提供了可靠实验依据，为粘土岩宏细观研究提供了良好借鉴。