冻融循环下咸寒区渠道防渗膜渐进破坏机理及损伤修复研究

The long-distance water supply channels in the northern cold and salty areas are seriously affected by harsh environments such as extreme low temperatures, transient temperature differences, and sulfate media erosion. In order to improve the water retention rate of the water channels in the salt-cold area and ensure the safety of the channel water conveyance project, it is urgent to conduct in-depth research on the damage mechanism and repair technology of the channel impermeable membrane in the complex environment of the site. This project intends to address the freeze-thaw aging problem of canal seepage membranes in salt-cold areas, and conducts indoor and field tests under conditions of large temperature difference freeze-thaw cycles and salt water operation. Accelerated freezing and thawing aging methods are used to study the number of freeze-thaw cycles and the temperature change rate. The influences of factors such as humidity, concentration of sulphate medium on the damage process of channel seepage membranes, and the change of micro-characteristics and physico-mechanical indices were analyzed to reveal the evolution process and progressive failure mechanism of channel impermeable membranes. Introduce the concept of surface modification of the impermeable membrane, perform plasma modification on the surface of the membrane, improve the polar groups of the material, and form covalent bonds with the binder molecules. Study the new technology of surface modification of the impermeable membrane Membrane seam joint serviceability, research and development of new and old impermeable membrane integration of new technologies. The research results of the project can significantly improve the water supply efficiency of the channel and provide technical support for the long-term safe and stable operation of the channel.

北疆咸寒区长距离供水渠道受极端低温、瞬变温差、硫酸盐介质侵蚀等恶劣环境影响严重。在极端气候下渠道防渗膜极易冻害老化，但目前其破坏机理尚不明确，因此急需对冻融循环下渠道防渗膜破坏机理及修复机制展开深入研究。本项目拟针对咸寒区渠道防渗膜冻害老化问题，开展在大温差冻融循环、咸水运行条件下的室内试验和现场试验，采用加速冻融老化手段，研究冻融循环次数、变温速率、湿度、硫酸盐介质浓度等因素对渠道防渗膜冻害破坏过程的影响，通过分析微观特征指标和物理力学指标变化规律，揭示渠道防渗膜性能演化进程和渐进破坏机制。引入防渗膜表面改性思路，对膜体表面进行等离子改性，提高材料的极性基团，与粘合剂分子可能形成共价键,构建防渗膜表面改性新方法，提高新旧防渗膜接缝服役性的可靠性。项目的研究成果可显著提高渠道的供水效率,为渠道的长期安全稳定运行提供理论支撑。

北疆咸寒区长距离供水渠道受极端低温、瞬变温差、硫酸盐介质侵蚀等恶劣环境影响严重，在极端气候下渠道防渗膜极易冻害老化。本项目在现场调查基础上，在咸寒区的季节性长周期大温差、长期浸泡和水位变动等运行环境条件下，对咸寒区渠道土工膜进行了系统、深入的试验分析，研究土工膜材料的力学性能的动态变化规律，分析其动态变化与外界环境因素的关系。项目结合相关工程开展了复合土工膜现场取样试验及室内加速老化试验。对试验材料分平均水位以上、平均水位线以下及水位线变动区域三种试验条件，开展室内试验。同时设置高温至低温的周期温度循环，模拟高变温、低变温速率下循环温度作用对土工膜耐久性指标的影响。项目针对工程中出现的新旧土工膜不易形成有效搭接的问题，选择万能胶、沥青、KS胶以及套筒等不同搭接方式，对新旧土工膜搭接缝进行物理力学、水力学及长期耐久性试验。通过对比试验结果，选取最优的新旧土工膜连接材料用于渠道升级改造，针对渠道升级改造作业中新旧土工膜的有效连接问题，研发了一套适用于高寒区渠道新旧土工膜一体化的连接技术。本项目在咸寒区渠道防渗土工膜方面的相关研究成果为高寒区渠道升级改造与维护技术提供了有力支撑。共发表学术论文6篇，会议论文1篇；其中SCI检索论文2篇，EI检索论文3篇，其中第一作者或通讯作者论文4篇。授权发明专利1项，实用新型专利2项。参与出版专著3部。