大岗山水电站泄洪洞顶层大断面爆破开挖

摘要

针对大岗山水电站泄洪洞开挖断面大的特点,结合现场地质条件,设计断面分四层开挖,其中顶层开挖分为左侧先导洞和右侧扩挖.针对顶层开挖选择了合理的爆破参数、装药结构及爆破网路.爆破取得了良好效果,光面爆破后永久面成型平整,几乎无超、欠挖,各类围岩光爆孔半孔率均高于规范要求,爆破振动小.为同类爆破施工工程提供了借鉴.%Aiming at the feature of large section in Dagangshan hydropower station flood-discharge tunnel , it was designed to divide the excavation section into four layers by combining with local geological conditions. The top excavation was divided into left pilot heading excavation and right enlarging excavation. Reasonable blasting parameters, charge structure and blasting circuit were chosen according to the top excavation . The good effect of blasting was obtained. After smooth blasting, permanent tunnel section was smooth and almost had no overbreak or underbreak. The half hole rates of smooth blasting holes in different surrounding rocks were higher than code requirement and blasting vibration was small. It could provide a reference to similar blasting engineering.