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

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.