Study On Seismic Responses And Vibration-Absorption Measures For Large-Diameter Shield Tunnel

With the development of city construction and underground space exploitation, abundant underground buildings are being constructed. However, due to the lack of basic information, a mature method for the seismic design of underground structure is absented yet. The seismic design code for subway in our country isn't yet comprehensive. These make the research on the seismic design of underground structures more important and urgent. Shield tunnels have been widely used in many infrastructure construction fields in China, such as undersea tunnel, underground railroad. The existing damage records show that great loss would be inevitable if tunnels are destroyed during earthquake. Earthquakes frequently occur in our country, hence it's necessary to deeply study the seismic responses of shield tunnels.In this paper, the summary of worldwide typical instances of tunnels behavior during earthquake, the developments and available methods were briefly described, the characteristics regarding the tunnel damages during earthquake and classification were summarized, and the damage mechanism of shield tunnels from earthquake was described. Based on Shantou undersea tunnel, the finite-difference computing software FLAC3D was used to investigate the dynamical reaction principles of the surrounding rock and the tunnel support systems, several aspects such as different typical flame, different segment joint, lining thickness and different lining material were considered. The damping effect of each measure was studied and evaluated by using the numerical method and the optimum method, and the vibration-absorption measures for shield tunnel were discussed. The content of this paper includes:First, great data of earthquake disaster of tunnel and underground structure in home and abroad were classified, analyzed and studied. The seismic failure mode, the influence factors and failure mechanism were concluded.Second, deep study on the seismic responses of the tunnel body under different segment joint, lining thickness and lining material was carried out by using FLAC3D simulation. By analyzing the stress, strain and displacement of tunnel lining in earthquake, the work statues of tunnel could be estimated.Last, different vibration-absorption measures were analyzed and compared for shied tunnel, and the damping effect of different measures were evaluated by numerical simulation method, thus the optimum method of vibration-absorption for tunnels was discussed.