大岗山水电站右岸拱肩槽开挖质量控制

Quality control of right bank arch dam abutment excavation of Dagangshan Hydropower Station

大岗山水电站大坝为双曲混凝土拱坝,对坝肩开挖质量要求高。坝肩部分高程需进行垫座置换开挖,且建基面为5个折线型开口坡面,预裂施工难度大。经施工方案比选并优化,确定了自上而下梯段爆破,由推土机集渣用反铲甩渣至大坝基坑的施工方案。通过强化过程控制对超欠挖、平整度、残孔率、质点振速等指标进行严格控制,保证了拱肩槽开挖质量达到优良水平。

Dagangshan Hydropower Station is a double - curvature dam that requires a high excavation quality on abutment. The replacement excavation is needed for partial foundation cushion of the abutment and the foundation surface are in 5 polyline type, causing difficulties of pre -splitting construction. Through comparison and selection, the construction scheme of excavation by bench blasting from top to bottom, ballast collecting by bulldozer and dumping into foundation pit by backhoe was adopted. The quality key points including over excavation and under excavation, flatness, residual pore ratio, particle vibration velocity were controlled strictly through emphasizing the process control, and the excavation quality reached an excellent level.