【摘要】 以国道318线黄草坪2#隧道为原型,开展大型三维振动台模型试验,重点研究隧道结构的地震动力响应规律及隧道与围岩的相互动力作用。通过对模型试验的关键技术研究,建立一套山岭隧道大型振动台模型试验设计、制作、加载及测试的工艺与方法流程。模型震害分析表明:隧道洞口边坡以开裂和滚落石震害为主,坡面加速度沿高程方向递增且具有一定的放大效应,在坡面原生裂缝和薄弱部位极易出现震害;隧道结构以衬砌开裂和掉块震害为主,初期支护和二次衬砌出现裂缝的部位不同,但钢筋网能够有效地阻止裂缝的发展。模型试验结果表明:隧道结构的加速度响应要大于周边围岩且对周边岩土体的加速度响应有一定的放大效应;对于一般的硬岩质山岭隧道来说,隧道洞口段0~50 m范围的加速度响应较大,为隧道抗减震设防的重点区域;山岭偏压隧道横向不同部位的地震动力响应存在明显差异;当地震波从隧道底部小角度入射时,隧道结构的加速度响应最强烈,对隧道结构的安全性是非常不利的;随着加载地面峰值加速度(PGA)的增大,隧道不同部位的加速度响应增大,但当隧道结构进入非线性破坏状态后,PGA呈减小趋势,地震能量逐渐被耗散。更多还原

【Abstract】 Taking Huangcaoping Tunnel No.2 of National Highway No.318 as a background,a large-scale 3D shaking table model test was carried out to understand the tunnel structure seismic responses and the tunnel-surrounding rock interaction.The procedures of design,manufacture,loading and test of the large-scale mountain tunnel model test were described associated with key technical issues in the model test.Seismic damage analysis of the model test shows that the main seismic damages of the tunnel entrance slope are of crack and rock falling,the slope acceleration along the elevation direction gradually increases and has a certain amplification effect;and the native cracks and weak parts on the slope are easy to be damaged;the main seismic damages of the tunnel structure are of crack and lining drop;the performance of seismic damage with initial support and secondary lining is different;and steel mesh can effectively prevent the propagation of cracks.The model test results also show that the acceleration response of the tunnel structure is greater than the surrounding rocks,and the tunnel structure leads to the amplification of the seismic response of the surrounding rocks.Basically,the acceleration response of the 0–50 m section from the entrance for mountain tunnel in hard rock is greater than that in other sections of the tunnel;and a main seismic resistance mitigation should be adopted in this section;the seismic responses of left and right side walls of unsymmetrically loaded tunnel is significantly different.Vertical and nearly vertical incident earthquake waves from the bottom of the tunnels cause strong responses of the tunnels,which is unfavorable for the tunnel safety.With increasing loading peak ground acceleration(PGA),the acceleration of the different parts of the tunnel structure increases gradually,but when the tunnel structure comes into the nonlinear failure,the PGA of tunnel structure shows a decreasing trend,and the seismic energy is dissipated gradually.更多还原