控制爆破技术在龙滩水电站地下厂房开挖中的应用

龙滩水电站地下厂房开挖时,为解决大跨度顶拱施工的安全问题、高直立边墙的稳定问题及岩锚梁开挖的质量问题,设计规定爆破质点振动速度不得大于7cm/s,为此,采取分层控制开挖的措施,采用预裂爆破、单孔微差挤压爆破技术以减小爆破质点振动速度。监测结果显示,爆破质点振动速度控制在设计允许范围内,在整个地下厂房开挖过程中和开挖后围岩的位移值控制在允许范围内。

Application of Controlled Blasting to the Excavation of the Underground Powerhouse of Longtan Hydropower Station

During the excavation of underground powerhouse of Longtan Hydropower Station, the design stipulated thep particle vibrating velocity is less than 7 cm/s in order to solve the safety of large-span top-arch construetion; the stability of high and vertical sidewall and the excavation quality of rock anchorage beam.Therefore,the measures of excavation by layer.pre-split blasting and single-hole millisecond crushing blssting have been taken.The monitoring results showed that the particle vibrating velocity is controlled in the design allowance and the displacement value of whole underground powerhouse in and after the excavation is controlled in the allowance.