三峡工程二期围堰拆除施工难点及对策

二期围堰拆除工程量大，工期紧，开挖强度高（水下达到30m^3/月），施工船舶多，塑性混凝土防渗墙钻爆技术难度大，围堰拆除与长江航运及主体工程施工存在干扰。必须进行认真的科学试验，并加强水上作业安全，加强协调管理，努力做好施工组织，才能确保围堰拆除工程顺利进行。

Removal of second-phase cofferdams at Three Gorges project

Considering removing work of the second phase cofferdams, characterized by vast removing quantities, tight time schedule, high excavation rate (up to 300 000 m 3/month for underwater excavation), too many construction boats within the construction area, big difficulties in blasting of the plastic concrete core walls and interfering of removing of the cofferdams with the shipping on the Yangtze river and the construction of the main works for the Three Gorges project, it is necessary to conduct a series of scientific experiments, take care of the safety of operation underwater, strengthen coordination management and construction organization, so as to ensure the successful removal of the second phase cofferdams at the Three Gorges project.