广蓄二期尾水洞不良地质段大断面开挖施工

Large-section excavation of the area with poor geological conditions in the construction of tailrace tunnel of Guangzhou Pumped Storage Plant (second stage)

广州抽水蓄能电站二期工程尾水洞出口段开挖施工针对围岩软弱破碎、地下水渗漏量大、浅埋隧洞及水下大断面开挖的特点 ,采用从地表预先灌浆、洞内超前预灌浆、从地表往下打锚杆预先锚固、洞内超前锚杆、超前管棚支护、先墙后拱法分部开挖、分部分台阶开挖、喷锚支护跟进掌子面等工程措施和施工方法。依据不同地质条件采用不同施工方法或几种方法联合应用 ,灵活调整喷锚支护参数 ,并采用变形监测指导施工 ,洞内未发生任何塌方。

In accordance with the characteristics of soft and crushed surrounding rocks, large groundwater leakage, shallow-buried tunnel and large-section underwater excavation, the construction and excavation of the outlet section of tailrace tunnel of the Guangzhou Pumped Storage Plant (second stage) adopted the following measures and construction methods such as surface pre-grouting, inside-tunnel pre-grouting, surface pre-anchorage, inside-tunnel anchorage rod in advance, support for pipe shed in advance, separate excavation in the way of first wall and second arch method, bench excavation in parts, shotcrete anchorage support following the heading face. All these methods and measures were separately or jointly adopted according to different geological conditions. The deformation observation was used to guide the construction so that there is no landslide inside the tunnel.