| The mechanism of soil-subway-tunnel interaction is complicated due to earthquake, which has a significant influence on the dynamic response of subway tunnel. It has great theoretical and practical value. Based on the combination of centrifuge model test and numerical analysis, the preliminary study to the seismic response rule of subway tunnel had been conducted. Main research work of this paper including the following several aspects:Firstly, several centrifuge tests were processed using the centrifuge shaking table of Tsinghua University. Based on the results of tests, some of the mechanism of seismic response of subway tunnel was obtained. The following were analyzed in detail: (1) The distribution of additive moment of subway tunnel due to earthquake was antisymmetric about axis of cross section. The maximum value often appeared in the'X'zone of cross section which had 45 degrees angles with axis of cross section. And the additive moment due to earthquake was smaller at top, bottom, left and right of the tunnel section. (2) The additive moment due to earthquake increased with increasing burial depth. (3) The maximum moment of subway tunnel always appeared in soft clay layer in both two-layered -ground model tests. (4) The additive moment of double-hole parallel subway tunnel due to earthquake was smaller than that in single-hole tunnel.Secondly, seismic response of free-field and soil-tunnel system was analyzed by equivalent viscoelasticity analysis method and was compared to the results of centrifuge model tests. It showed that this analysis method is effective when it is used to analyze rule of seismic response of field and subway tunnel. It provides the effective method for seismic response research of complex subway underground structure.Finally, a dynamic analysis model of soil-tunnel system was set up based on Beijing Metro Line 5. The seismic response of the subway tunnel was analyzed by equivalent viscoelasticity analysis method. The influence of burying depth and nature of soil was also discussed. The following were analyzed in detail: (1) The maximum value of additive moment appeared at the two sides of arch which had 45 degrees angles with axis of cross section and the attachment points of the vertical walls and floor under earthquake function. (2) The additive moment due to earthquake increased with increasing burial depth under the test condition. (3) It is advantageous that soil texture condition of following stratum is good when regarding tunnel's earthquake resistance in the earthquake. |
