强震作用下岩石场地群洞地铁车站试验研究

Experimental Study of Tunnel-group Metro Station on Rock Sites under Strong Ground Motions

摘要:

为探究岩石场地群洞地铁车站在地震作用下的动力特性，设计了一个比尺1∶30的群洞地铁车站结构的大型振动台试验模型，通过采用横向输入峰值加速度0.07g、0.15g、0.21g、0.30g、0.50g、0.70g和1.0g等7个不同强度的人工地震波，研究了群洞地铁车站在强震作用下的加速度响应特征、位移响应特征、结构破坏模式和动应变响应特征。结果表明：阿里亚斯强度（Arias Intensity）的放大系数曲线揭示，模型围岩和站厅衬砌结构在峰值加速度0.5g 后进入塑性破坏状态；站台衬砌结构在峰值加速度0.3g后从塑性状态逐步进入破坏状态，同时能量耗散逐渐增加。 随着地震动强度的增大，站厅横断面的相对位移增幅显著，开口断面与非开口断面的相对位移峰值差距进一步扩大。结构的裂缝主要分布在纵向，站台直墙中部纵向裂缝宽且长，而站厅直墙中部未产生明显裂缝。结构传递函数的主频随着地震动强度逐渐减小，在弹性阶段和塑性破坏阶段，结构主频分别为22.7、18.5 Hz。当地震动横向激励时，VL断面相同位置的拉应变均大于HR断面，最大拉应变出现在竖向联络通道的下断面拱肩处。

Abstract:

To investigate the dynamic characteristics of the tunnel-group metro station on rock sites under ground motions, a large-scale shaking table test model of the structure was designed at a scale of 1∶30. Seven artificial seismic waves with different intensities, having peak accelerations of 0.07g, 0.15g, 0.21g, 0.30g, 0.50g, 0.70g, and 1.0g, were applied horizontally to investigate the accelera tion response characteristics, displacement response characteristics, structural failure modes, and dy namic strain response characteristics of the tunnel-group metro station under strong ground motions. The results showed that the amplification factor curve of Arias Intensity revealed that the modeled sur rounding rock and the station hall lining structure entered the plastic failure state after a peak accelera tion of 0.5g. The platform lining structure gradually transitioned from a plastic state to a failure state after a peak acceleration of 0.3g, accompanied by a gradual increase in energy dissipation. As seismic intensity increased, the relative displacement of the station hall cross-section increased significantly, and the difference in peak relative displacement between the open and non-open sections further wid ened. Cracks in the structure are primarily distributed longitudinally. Wide and long longitudinal cracks were observed in the middle of the vertical walls of the station platform, while no significant cracks ap peared in the middle of the vertical walls of the station hall. The fundamental frequency of the structur al transfer function decreased with the increase in seismic intensity, with fundamental frequencies of 22.7 Hz in the elastic phase and 18.5 Hz in the plastic failure phase. Under lateral seismic excitation, the tensile strains at the same locations in the VL section were greater than those in the HR section, with the maximum tensile strain occurring at the lower arch shoulder of the vertical connecting passag es.