三板溪水电站导流洞进口不良地质洞段开挖施工

Excavation of the Section With Bad Geological Conditions of The Inlet for Division Tunnel of Sanbanxi Hydropower Station

三板溪水电站导流洞为特大断面的隧洞,其进口段洞身的地质条件较复杂,节理裂隙比较发育,洞顶楔体密度大且最大楔体体积达1 100 m3。本文介绍该导流洞进口段洞身开挖与支护的主要施工方案与施工工艺,即导流洞洞身开挖自上而下分2层施工,先进行上层中导洞开挖和扩挖,然后再进行下层扩挖,喷锚支护则紧随开挖进行;开挖时严格执行设计规定的“密孔、短井尺、小药量、弱爆破”的原则,使整个开挖满足了安全、质量、施工总进度的要求。

The diversion tunnel of Sanbanxi Hydropower Station is one with super-big section. The geological conditions of the tunnel body at inlet block are very complex, there joints and fissures have be developed and the density of wedge blocks are large, the volume of the biggest wedge block is up to 1, 100 m^3. The paper introduces main schemes and process of construction for excavation and supporting at inlet block in the tunnel body, such as layering excavation, supporting close to excavation, following the principle of excavation blasting-“small hole distance, small headway, small blast and weak blast”, etc.