Snakeskin Trench Tunnel Construction Impact Study On The Stability Of The Existing Tunnel

With the development of railway, more and more new multiple track projects will be put into construction. Usually, the new railway tunnels are designed in the proximity of the existing adjacent tunnels because of the restrain of the topographical and geological conditions, and the proximity blasting of the construction of the new tunnels would be harmful to the existing tunnel. The research on structural safety of the existing tunnel affected by the construction of the new adjacent tunnels are particularly important.Based on the Shepigou tunnel project from Xiangfan to Chongqing multiple track railway, the stability of surrounding rock of the existing adjacent tunnel has been analyzed through monitoring measurement and numerical simulation. First, the data information , including the constringency displacement, the surface strain of lining and the blasting vibrational velocity, has been analyzed comprehensively, and the effects that the new tunnel would impose upon the existing adjacent tunnel and the rationality of the blasting parameter have been evaluated through the empirical criterion. Then, considering three working and load conditions, the distribution of stress and strain of the existing tunnel surrounding rock have been simulated, and the comparison between the analogue result and the spot observation data has been done. It is found that the maximum effect occurs on the tunnel wall facing the blasting side, arch bottom and arch section of the existing tunnel under the action of blasting. After the new tunnel has been excavated or under the action of blasting the existing tunnel is stabile. And the trends of the vibration of the lining strain from numerical simulation and from spot observation are correspondent...