嘎隆拉隧道洞口段地震响应大型振动台模型试验研究

摘要

洞口段为隧道抗震关键位置,极其容易发生地基失效及结构破坏.通过对嘎隆拉隧道洞口段轴向100 m开展大型振动台模型试验研究,研究结果表明:土体对其卓越频率附近的地震波有明显的放大作用,对地震波高频部分有滤波作用;地震时隧道与土体同步振动,不表现出自身的固有振动频率,惯性力对地下结构地震反应影响不大,故隧道抗震研究的重点是地震下围岩的失效防治,结构抗震设计主要目的是减小围岩失效对隧道产生的破坏;减震层和抗震缝的设置都不会改变结构地震反应的频谱特性,但设置减震层后,结构的峰值加速度增加,加速度放大系数不能作为减震效果的评判依据.研究成果对隧道的抗震设计和减震设计有重要工程应用价值.%As the key position of tunnel seismic design, the portal section is extremely vulnerable to foundation failure and structure damage.The longitudinal distances of 100 m in portal section of Galongla tunnel are selected as the prototype to conduct large-scale shaking table test.The research results are shown as follows: (1) The soil around tunnel has obvious amplification effect on the input seismic waves with the frequency near the predomination frequency of soil; and also it has filtering effect on the input seismic waves with high frequency.(2) The tunnel vibrates synchronously with the surrounding soil; and it doesn't show its own natural vibration frequency.The inertial force has little effect on underground structure's seismic response.So the key point of tunnel's anti-seismic research is failure prevention of surrounding rock under the earthquake; and the main purpose of structure's aseismic design is to reduce the structure damage from the failure of its surrounding rock.(3) The absorbers and aseismatic joints don't change the spectrum characteristics of lining; but they can increase the peak acceleration of lining.So, the damping effect should not be judged by the acceleration magnified coefficient at these places.The research results have important application value to aseismic design and shock absorption design of tunnel.