大型输水渠道衬砌在冻融循环等作用下易产生剥蚀破坏等缺陷，同时渠底反滤排水系统在运行过程中可能会失效，需要进行检修和维修。大型输水工程一般不具有停水或者降低水位运行条件，因此在不停水条件下渠道衬砌面板缺陷与破坏修复技术是大型调水输水工程检修、维护的重点和难点问题之一。以南水北调中线干渠衬砌修复现场试验为依托，进行了一种水下3.0~3.5 m钢围堰的结构设计，深入研究了挡水面板、支撑传力系统并进行了有限元受力分析，研究了不同部位结构新型止水型式，提出了便于安装且止水效果好的自平衡组合式围堰成套技术，以及钢围堰水面装配、入水就位及拆卸转场施工技术，并结合现场试验成果进行不断优化，可以为大型输水工程衬砌水下修复干地作业提供有益参考。

Large scale water conveyance canal lining is easy to erode and damage under freezethaw cycles and the drainage system at the bottom of the canal may fail during the operation processes.These disadvantages need to be improved.Large scale water diversion projects generally do not have the conditions of waterstopping or water level reduction.Therefore,the repairing techniques of the defects and damages under the condition of non-stop water are one of the key and difficult problems in the operational and maintenance of largescale water diversion projects.Based on the field testing of lining repair of main canal in the middle route of South to North Water Diversion Project,the structure design of an underwater 3.0~3.5 meter steel cofferdam was carried out.A set of self-balanced combined cofferdam techniques,which were easy to install and had effective water stopping,was proposed in this study through further researches of water retaining panel,supporting force transfer system and new water stopping types of structures in different parts..Construction technology of water surface assembly,waterentry and dismantling transfer site of steel cofferdam have also been proposed.The results can provide useful references for underwater repair of dry land with lining of large water conveyance projects.

国家重点研发计划(2017YFC0405006);国家自然科学基金(51878245)