Abstract :
This study presents seismic response of metro tunnel by taking on Beijing metro line 10. Various seismic propagation directions are considered respectively, such as horizontal, vertical and coupling effect of seismic direction. The results suggest that the inducing ground motion calculated be 192.1cm/s2 in teams of the only horizontal acceleration-time history. The corresponding amplification factor is 1.06. Under the condition of the sole vertical dynamic loading, the corresponding ground motion calculated is 99.5cm/s2 and corresponding amplification factor is 0.821. The peak value of acceleration calculated and the one applied at the rock outcropping of the deposit occur simultaneously. Occurring time of ground displacement peak lags behind that of acceleration applied at the rock outcropping of the deposit. Response induced by coupling loading is not significantly different from that by the sole horizontal loading. However, coupling loading has influence on acceleration peak induced by vertical seismic wave. Furthermore, only horizontal shearing action has been considered in previous seismic design, which is not safe for the engineering. Vertical acceleration would lead to great destruction, and should be taken into account in the process of seismic assessment. Not only does the analysis method fit for metro tunnel in Beijing stratum, but it can be used as reference for similar tunnel and underground engineering.
