小浪底水利枢纽工程2^#明流洞断层开挖

Fault excavation for free flow tunnel No. 2 of Xiaolangdi water control project

2#明流洞全长1105 m,其中下游洞长108 m,开挖断面为直墙圆顶的城门洞型,尺寸为宽12.4 m,高15.4 m,在桩号为0+472～0+515处有F240断层通过,稳定性极差。断层开挖采用短进尺、弱爆破、强支护、勤监测等施 工措施,成功地完成了施工任务。

Free flow tunnel No. 2 is 1105 m long and its downstream section is 108 m. The excavation section is in a reversed U shape 12. 4 m wide by 15. 4 m high. At station No. 0+481, 7 m3 debris collapsed during excavation. Therefore, the principle of short drilling footage, small blasting, strong support and frequent monitoring is adopted for the fault excavation.