滇中引水工程破碎围岩洞室开挖支护方案分析

Analysis of excavation and support technology of cavern in Central Yunnan Water Diversion Project under broken surrounding rock condition

为研究不良地质条件下的洞室开挖支护技术,以滇中引水工程三大主体工程之一的石鼓水源工程为例,针对该工程冲江河右岸进水隧洞与进水箱涵连接段地质条件较差,主要存在浅埋覆盖层与破碎岩体的变形与稳定问题,介绍了进水隧洞采取的开挖支护措施。在石鼓水源工程一期进水箱涵和右岸进水隧洞开挖时,对箱涵边坡采用竖向钢管桩支护措施,隧洞洞口采用超前大管棚、超前小导管、钢拱架锚喷支护、超前堵水灌浆多项支护措施,并对隧洞进行了混凝土衬砌施工。稳定性分析结果表明:该类支护方案能有效控制边坡变形和隧洞洞口收敛,适用于稳定性极差的Ⅴ类围岩进洞段开挖支护。

In order to study the excavation and support technology of the cavern under adverse geological conditions,Shigu Water Source Underground Pump Station,which was one of three main projects of Central Yunnan Water Diversion Project was taken as an example for research.Aiming at the problems of connection section between intake tunnel and box culvert on the right bank of Chongjiang River,such as poor geological conditions,and the deformation and instability of the soft surrounding rock in the shallow buried tunnel section,this paper introduced the excavation and support measures taken for the intake tunnel.During the excavation of the intake box culvert of first phase and the right bank intake tunnel of Shigu Water Source Underground Pump Station,vertical steel pipe piles were used to support the slope of the box culvert,and multiple support measures such as advanced large pipe shed,advanced small conduit,steel arch anchor spray,and advanced water blocking grouting were taken for the tunnel entrance.Concrete lining was also carried out for the tunnel.The results of stability analysis showed that this support scheme could effectively control slope deformation and convergence of tunnel openings,which was suitable for excavation support for Class V surrounding rocks with poor stability in tunnel entrance.