Study On Seismic Response Law And Damage Mechanism Of Subway Tunnels

In recent years, with population growth and urban development, manycities have fallen into the dilemma that ground space is not enough. Groundtransportation capacity is far from being able to meet people’s needs, so moreand more countries and regions have already developed or plan to developunderground space. The extensive underground space development brings a lotof problems to be solved. The seismic safety of underground structures isespecially significant. Underground structures have mechanical characteristicsand seismic responses very different from common structures on the ground,and the common seismic design methods are not suitable for undergroundstructures. Tunnel destruction has occurred many times in domestic andinternational earthquake. The seismic damage of underground structures maylead to huge casualties, and the underground structures are rather difficult torepair. Therefore it’s necessary to study on the seismic resistance ofunderground structures. Based on predecessors’ research, this paper mainlystudies on seismic response law and damage mechanism of subway tunnelsaccording to shaking table test and numerical simulation. Specific contents areput forward as follows:1. Analysis of seismic damage informationSeismic damage information of Kobe City’s underground structures in the1995Osaka-Kobe Earthquake is introduced; a few specific characteristics aresummarized; several seismic factors to underground structures in theearthquake are proposed.2. Constitutive models of soilSeveral common constitutive models of soil in Geotechnical Engineering;the secondary development of Duncan-Chang model is achieved in ANSYSaccording to APDL.3. Numerical simulation of near-field wave motionSeveral common artificial boundary conditions are introduced;viscous-spring artificial boundary and free-field boundary are applied inANSYS; the problems such as initial ground stress field and static-dynamicboundary transformation are solved. 4. Shaking table test of underground structuresThe cascading shear box and the overview of underground structures’shaking table test is introduced; the automatic processing of shaking table testdata is programmed on the on the basis of FORTRAN90and MATLAB; byanalyzing the results of ‘tunnel through interface of soil’ shaking table test,several conclusions about seismic responses of tunnels are made.5. Numerical simulation of tunnel’s seismic responsesNumerical simulation of circular tunnel’s seismic responses is carried outin ANSYS; the simulation results are compared with analytical solutions; howthe seismic factors affect tunnel’s seismic responses is analyzed; severalcommon seismic failure modes of tunnel and the failure mechanism aresummarized.