大岗山大坝左岸拱肩槽开挖施工技术

Excavation technology of abutment groove at left bank of Dagangshan Hydropower Station

大岗山水电站大坝所在区域地质状况复杂,断层、软弱带层较多,岩体切割分层面多而广,给工程施工造成了较大的难度及安全隐患。针对坝肩槽开挖设计轮廓几何尺寸要求高,建基面岩体质量控制、爆破振动、声波衰减控制要求严,钻爆工程量大,长缓坡开挖难度大等开挖特点,设计了自上而下分层,从外到内分区、分块进行开挖的总体方案,并对施工所需的各项机具进行了合理的技术改造。介绍了基本施工方法和爆破试验情况。

The geological condition of Dagangshan Dam site is complicated with many faults and weak layers,which brought difficulties to the construction and threatened the dam safety.In the light of the characteristics of the strict requirement of the excavation size,the quality control of the foundation planes,blasting vibration control,acoustic wave attenuation,and large amount of drilling and blasting and difficult excavation of long and gentle slopes,the outside-in and top-down excavation was designed as the general scheme.The required construction tools were technically improved.The basic construction method and blasting tests were introduced.The summary of pre-splitting over-break balance construction method and drilling-blasting parameters shows that the construction efficiency and quality are greatly improved and the cost is reduced.