含连拱隧道边坡地震响应特性研究

Study on seismic response characteristics of slope with double-arch tunnel

利用MIDAS GTS有限元软件建立一个含连拱隧道软弱围岩边坡模型,并利用振动台试验进行验证,探究了含连拱隧道边坡地震响应特性,分析了隧道的存在和隧道的位置对边坡动力响应特性的影响。得出以下主要结论:(1)边坡加速度放大系数沿坡高向上表现出非线性变化趋势,并表现出趋表效应。坡体底部测点卓越频率为7Hz,顶部测点卓越频率为4.8Hz,说明边坡削弱地震波高频段,放大低频段并改变其频谱成分。(2)含连拱隧道边坡加速度放大系数最大值为2.04,不含隧道边坡加速度放大系数最大值为1.88。含连拱隧道边坡加速度响应的非线性特征更明显,更不利于边坡稳定。连拱隧道的存在使得边坡受力不确定性增加,边坡动力响应更加复杂。(3)连拱隧道位置不同,对边坡的地震动力响应特性也不尽相同。连拱隧道距坡面越近,边坡受到的影响越大,越不利于边坡稳定。研究结果对含连拱隧道边坡抗震设计有一定借鉴意义。

In order to study the dynamic response characteristics of the soft surrounding rock slope with double-arch tunnel under earthquake,a numerical model of the soft surrounding rock slope of double-arch tunnel is established by using MIDAS GTS finite element software,and the validity of simulation is verified by shaking table test.At the same time,the influence of tunnel location and existence on dynamic response characteristics of slope is studied.The results show that,firstly,along the slope surface upward,with the increase of slope height,the acceleration amplification coefficient changes nonlinearly,and the surface effect appears.The predominant frequency at the bottom of the slope is 7 Hz,and that at the top is 4.8 Hz.The high frequency band of seismic wave was restrained by slope and low frequency band was enlarged.Also the spectrum composition of seismic wave was changed.Secondly,the maximum AAC of the slope with double-arch tunnel is 2.04,and the maximum AAC of the slope without tunnel is 1.88.The non-linear characteristics of the acceleration response of the slope are more obvious,and the acceleration response is greater than that of slope without tunnel.Due to the existence of double-arch tunnel,the uncertainty of slope forces increases and the dynamic response of slope became more complex.Thirdly,due to different locations of double-arch tunnel,seismic response characteristics of slope is different.The closer double-arch tunnel is to the slope,the greater the impact on the slope,and the more unfavorable to the slope stability.The results of the study can be used for the study of seismic resistance of slope with double-arch tunnel.