地铁营运期盾构隧道管片块位移响应分析

Analysis of Displacement Response of Segments of Shield Tunnel due to Vibration of Metro Train

采用FLAC3D三维动力计算软件,充分考虑接缝、管片分块和复杂地层等因素,对广州某埋置于软硬交错地层之中的盾构隧道在地铁营运列车振动荷载作用下各管片块位移响应问题进行深入分析。结果表明,地铁列车一组组轮对的滚过所产生的加卸荷和振动效应导致各管片块的位移响应出现起伏波动现象,环底附近的管片块位移响应最大,自环底向环顶逐渐减弱,管片整环发生轻微垂向椭变响应。管片块位移响应强度与其所处地层的性质紧密相关,在软土地层中管片环位移响应最大,其椭变最明显。

The elastoplastic 3D dynamic finite difference model was established by using FLAC3D numerical software. By fully considering the factors of the joints, the segments and the complicated stratum, the displacement response of the segments of shield tunnel buried in the complicated stratum under the vibrating load induced by a metro train was numerically simulated. The simulation results show that, the load-on and load-off and the vibration induced by the train wheel wiling results in the rising and falling to fluctuation of the displacement response of each segment. The severe displacement response zones of the segment-structure are largely distributed in the range of the lower half of the segment-ring and the nearer to the bottom of the segment-ring, the more severe the response. The whole segment-ring presents ellipsoidal response. The intensity of the response is related close with the mechanics property of the stratum surrounding. The tunnel being buried in the soft stratum results in the maximum of displacement and ellipsoidal response of the segment-ring.