寒区渠道冻土-混凝土衬砌结构相互作用机制及多场耦合冻胀破坏模型

Canal system is ‘lifeline’ of oasis’ agriculture in south of Xinjiang. The lining canals are damaged by frost heave seriously which leads to a large amount of water conveyance loss. The damage has become a critical and technical problem restricting the irrigation areas’ healthy development. The frost heaving damage of lining canals is the result of foundation soil’s heat-moisture-stress fields’ coupling effect and its interaction with the concrete lining structure. This proposed research aims to understand the frozen soil-concrete interface’s mechanical characteristics by carrying out static direct shear tests. Combining indoor model tests and the non-linear finite element analyses, this study will present the interaction mechanisms between the frozen soil and the concrete lining structure. Based on the interaction mechanisms and lining canal’s prototype monitoring tests, the research will synthetically considers meteorology, soil properties and underground water table and so on. The evolution rules of the occurrence, development and destruction of the lining structure will be analyzed, which are influenced be heat-moisture-stress fields’ coupling effect. After comprehension of the above achievements, the research will build the frost damage model of lining canals. It is hoped that the outcome of the research will provide theoretical and technical support for the design and frost damage prevention of canal system engineering in cold regions.

渠系输水系统为南疆绿洲农业的“生命线”。塔里木灌区衬砌渠道冻胀破坏剧烈，造成大量的输水损失，成为制约灌区健康发展的关键技术难题。衬砌渠道冻胀破坏是渠基冻结过程中水热力三场耦合变化及其与混凝土衬砌结构相互作用的结果。本项目开展冻土-混凝土接触面静力直剪试验，着力研究接触面力学特性，运用室内模型试验和非线性有限元数值分析技术，揭示冻土-混凝土衬砌结构相互作用机制。在此基础上，综合考虑灌区气象、土质和地下水位等因素，结合原型监测试验，分析水热力耦合作用下衬砌冻胀变形发生、发展以致破坏的演变规律，建立渠道冻胀破坏模型，为寒区渠系工程设计与冻胀病害防治提供理论支撑和技术保障。

渠系输水系统为南疆绿洲农业的“生命线”。塔里木灌区衬砌渠道冻胀破坏剧烈，造成大量的输水损失，成为制约灌区健康发展的关键技术难题。衬砌渠道冻胀破坏是渠基冻结过程中水热力三场耦合变化及其与混凝土衬砌结构相互作用的结果。项目通过对灌区衬砌渠道破坏调研，总结了渠系破坏特征；采用冻土-混凝土接触面直剪试验，探讨了接触面粗糙度、含水率和冻结温度等因素对接触面强度的影响规律；基于室外渠道模型试验，观测了自然环境对衬砌板表面温度和地温的影响，获得了冻深分布规律，特别是衬砌板变形和裂缝发育特征；开展室内土柱封闭-开放系统冻融循环试验，监测了温度梯度作用下土体水分迁移规律及其对冻胀变形的影响。结合室内试验、室外模型试验、理论分析和多场耦合理论，揭示了衬砌结构冻害机理，建立了考虑环境-渠基土-衬砌结构相互作用的衬砌渠道冻胀破坏模型，为寒区渠系工程设计与冻胀病害防治提供理论支撑和技术保障。本项目已发表学术论文5篇，其中EI收录2篇。