偏压隧道模型振动台试验与数值模拟研究

摘要

根据动力模型试验相似关系,设计了一个比尺为1:10的偏压隧道模型,开展大型振动台模型试验,研究地震作用下偏压隧道加速度动力响应规律,模型试验以汶川波作为输入波,采用水平(X)向、竖直(Z)向和水平竖直(XZ)双向3种加载方式.利用MIDAS/NX有限元软件进行数值模拟,并与模型试验结果对比分析.研究表明:衬砌测点的加速度时程曲线与输入地震波特征相似,卓越频段和傅氏谱谱值都增大.X向激振时,加速度放大效应不明显且放大系数随激振幅值的增大而略有减小;竖向波对衬砌加速度动力响应影响明显大于水平地震波,表现为加速度放大效应显著;XZ双向激振时,相比于单向波而言测点加速度放大系数有增大、也有减小,与测点位置有关,临近边坡侧测点竖向加速动力响应较大,非偏压侧拱脚和拱顶是抗震设计的重点;数值模拟与试验结果在变化趋势上相近,数值上拟合程度高,在输入Amax＜0.2g时,模拟结果误差较小,随输入加速度峰值的增大误差增大.%Based on the similar relationship of dynamic model test,a large-scale shaking table model test of a unsymmetrical loading tunnel model with the geometric scale of 1:10 was performed to study the acceleration dynamic response under earthquake loads.Wenchuan seismic wave with three excitation directions including horizontal(X) direction,vertical(Z)direction and horizontal and vertical(XZ)direction were used as the excitation waves in the model test.Numerical simulation was carried out by MIDAS/NX finite element software and the results of numerical simulation and model test were contrasted analysis.The results show that acceleration time-history curve of measuring points are similar to the input seismic wave characteristics,excellent frequency range and Fourier spectrum value has increased.In X excitation,acceleration amplification effect is not obvious and amplification factor decreases with earthquake amplitudes increasing.The vertical seismic wave effects on dynamic response acceleration of lining significantly greater than horizontal seismic wave and acceleration amplification effect is more obvious.In XZ excitation,some of acceleration amplification factor of measuring points increase and others decrease comparing with one-direction wave.The vertical acceleration dynamic response of measuring points which are close to the slope are greater than others.The arch foot of unbias side and arch crown are the key of seismic design.The results of numerical simulation and model test have similar alteration trend and the numerical fitting degree is high.When Amax ＜0.2g,simulation result error is small,but error increases with the increase of input peak acceleration.