软土地基盾构隧道地震动力响应振动台模型试验研究

Shaking Table Test for Seismic Responses of Shield Tunnel in Soft Soil Foundation

历次发生的大震表明,软土地基会增大地震作用的破坏程度。以某软土地区地铁盾构隧道为原型进行振动台模型试验,重点分析隧道结构的动力响应特性及隧道与围岩的相互动力作用。试验分析表明:地震波在土体中的传播特性因隧道结构的存在而发生了改变,隧道的存在对其周围土体和地表的加速度峰值有一定的减小作用。隧道结构应变值在距离拱顶和拱底圆心角为±30°处相对于其他部位较大,这些部位易发生破坏。因此,在隧道结构设计中应适当提高这些部位的抗震措施。

All previous occurrence of strong earthquakes showed that soft soil will increase the damage degree of earthquake. A subway shield tunnel in soft soil area was used as a prototype for shaking table model test,the dynamic response characteristic of the tunnel structure and the dynamic interaction of the tunnel-surrounding rocks was analyzed. The results show that,propagation characteristics of seismic wave in the soil is changed due to the existence of the tunnel structure,and the tunnel structure results in the decrease of the seismic peaks of the surrounding rocks and earth surface. The damages are likely to occur at the places with central angles of ± 30° to the top or bottom of the tunnel structure,where the strains are larger than other places. Thus,seismic measures should be increased for the design of tunnel structure of these sections.