三峡工程三期上游碾压混凝土围堰拆除方案与实施

Demolition Scheme and Implementation of the Third Stage Upstream RCC Cofferdam for Three Gorges Project

三峡工程三期上游碾压混凝土围堰拆除的规模、总装药量及技术与施工难度均超过国内外已实施的围堰拆除,因爆破紧邻主体建筑物,为确保建筑物的安全,通过理论分析与模型试验,选取了以“倾倒为主,炸碎为辅”的拆除方案,由于爆破水深,为确保倾倒缺口的形成,由我国国内企业自主研制并使用了高威力、高抗水型的混装炸药,同时为防止爆破振动叠加,首次从国外引进了数码雷管实施控制爆破。根据安全监测成果和围堰拆除后的水下地形测量成果分析,围堰拆除设计方案是成功的,达到了预期效果。

The scale, total charge, technique and operated difficulty of the demolition of the third-stage upstream RCC cofferdam all exceed those of the implemented cofferdam demolition at home and abroad. As the blasting is adjacent to the main structures, in order to ensure the safety of the structures, the method of ＂taking dumpage as main and breaking into pieces＂ as complement one is adopted according to academic analysis and model test results. As the blasting water depth is deeper, mixed-loaded dynamite with high power and high water resistance that is developed by us is used to make sure the form of the dumpage gap. The digital detonator introduced from abroad is used to prevent the blasting vibration superposition. The demolition layout is successful and the prospective effect is achieved according to the analysis of the result of safety monitoring and underwater topographic survey after the demolition of the cofferdam.