Wushaoling tunnel is the longest single line railway tunnel in China up to now with the length of 20.50 km

and the F7 fault is the largest active fault

in which the geological conditions is highly complicated; it effects the tunnel construction badly. According to the characteristics of F7 fault and the problems met in tunnel construction

the stress and displacement of rock wall and lining structures were long term monitored after excavating in F7 fault section of Wushaoling tunnel. The trend of stress and displacement changing are analyzed based on the site monitoring results; and the mechanism of the extrusion large-deformation are explored so as to understand the regulation of stress releasing of rock wall and rock pressure. Furthermore

based on the site monitoring results

the optimized dynamic design and improved construction measure are proposed and adopted for the section at which the tunnel crosses the F7 fault. It not only avoided the large deformation occurrence

but also guaranteed tunnel drilling through the F7 fault section safely and quickly.