浅谈建基面保护层开挖方法的综合利用

Discussion on the Comprehensive Utilization of the Excavation Method for Foundation Surface Protective Layer

西藏大古水电站建基面开挖面积40217m2,基岩为黑云母花岗闪长岩,以Ⅱ类和Ⅲ类岩体为主,具有工程量大、岩质坚硬、质量要求高、结构面形式多变、工期紧等施工特点,结合以上施工特点进行综合考虑,建基面保护层开挖采用水平预裂爆破辅以浅孔梯段爆破法、孔底设置半球形刚性垫层的保护层一次爆破法。实践证明,该方案的综合利用不仅确保了施工质量、提高了施工效率,还有效降低了施工成本。

The excavation area of the foundation surface of Dagu Hydropower Station in Tibet is 40217m^2.The bedrock is biotite granodiorite,which ismainly of typeⅡand typeⅢ.It has the characteristics of large amount of engineering,hard rock,high quality requirement,changeable structural surface form,tight construction period,etc,.Combinedwith the above construction characteristics,the protective layerof the foundation surface is excavated by horizontal pre-splitting blasting supplementedwith shallowhole ladder blasting,and one burstmethod of protecting layer with hemispherical rigid cushion at the bottomof hole.The practice shows that the comprehensive utilization of this scheme not only ensures the constructionquality,improves the constructionefficiency,but also effectivelyreduces the constructioncost.