三峡二期下游围堰砼防渗墙复杂结构拆除爆破设计

Design of demolition blasting of complicated structure of concrete cut-off wall in second-stage downstream cofferdam of Three Gorges Project

三峡二期下游围堰拆除工程砼防渗墙部分墙段内有灌浆施工时预埋的灌浆钢管及固定钢管的保持架,这种结构在以往的围堰防渗墙爆破拆除工程中没有先例。工程进度要求2002年7月1日前完成爆破设计和爆破试验及现场所有准备工作,7月1日进行防渗墙拆除爆破,确保一次爆破成功。介绍了在总结以往经验基础上应用现场爆破试验成果所进行的砼防渗墙拆除爆破设计和爆破效果分析。

With a limited demolition duration and a great quantity of excavation under water, especially the fact that there were grouting steel tubes and holding frames within the concrete cut-off wall, the work of the demolition of structure was of great challenge. The blasting design, site tests and all locale preparatory work were demanded to be completed before July 1,2002 according to the given schedule, and the demolition of the cut-off wall was scheduled to be carried out on July 1 and must be successful. The design of the demolition blasting of the concrete cut-off wall that was based on other project's experience and the site testing is introduced in this paper, the analysis of the blasting effect is also presented.