高地热环境隧道混凝土衬砌结构损伤演化机制与耐久性退化

高地热环境中隧道混凝土衬砌结构，由于受到洞外高温地热水和洞内大气环境侵蚀的双向作用，耐久性损伤严重，并且高温地下水对混凝土衬砌的侵蚀速度快，可能导致靠近围岩外侧的衬砌已严重受损，但内侧衬砌表面并无明显损伤特征，产生极大的安全隐患。本项目以西部地区存在高地热水问题的隧道混凝土衬砌结构为研究对象，以地热水中多种离子对混凝土的侵蚀行为作为研究核心，围绕复合混凝土衬砌结构，分别对初期支护和二次衬砌结构在高地热环境中的耐久性问题开展系统研究。采用理论分析、快速腐蚀试验与工程验证相结合的方法，从高地热环境施工对衬砌混凝土微观结构影响分析入手，考虑多种高浓度离子、温度场、围岩压力的共同作用，研究混凝土中离子传输行为，分析混凝土微观结构变化，揭示高地热环境中复合混凝土衬砌结构耐久性损伤机理，建立多因素共同作用下衬砌结构耐久性退化模型。考虑地热环境中衬砌结构遭受内外双向腐蚀作用，建立隧道复合混凝土衬砌结构耐久性失效标准，提出耐久性寿命预测方法。项目研究成果将为高地热环境隧道结构的安全运营和全寿命设计提供理论依据和技术支撑。

The concrete lining structure in the high geothermal environment always seriously damaged due to coupling affection of geothermal water outside the cave and atmospheric environment inside the cave. Focuses on the corrosion problems of tunnel lining structure caused by geothermal water in western China, this project takes the erosion behavior of concrete caused by various ions in geothermal water as the research priority. The durability of composite in lining structures (including initial support and secondary lining structure) under the high geothermal will be systematically researched. The combination of theoretical analysis, rapid corrosion testing and field verification will be taken in this research. Based on the microstructure analysis of lining concrete under high geothermal environment, the combined effects of various high-concentration ions, temperature field, and rock pressure, ion transport behavior and microstructure of lining concrete will be investigated, the durability damage mechanism will be revealed, and the durability degradation model under multiple factors will be established. The durability failure criteria and the durability life prediction method which considering the couple affection of lining structure will be given. The results of this project will provide theoretical basis and technical support for the safe operation and life-cycle design of tunnel structure under high geothermal environment.