地震动输入方向对隧道洞口段动力响应的影响

摘要

隧道洞口段抗震分析中, 需要考虑地震动输入方向的影响.通过数值模拟的方法对不同地震动输入方向输入时隧道洞口段仰坡和衬砌的动力响应进行了对比分析.结果表明:横向地震动作用时隧道洞口段的动力响应最大, 纵向输入时次之, 竖向输入时最小;横向和纵向地震动作用时, 坡面位移放大系数 (PGD) 和加速度放大系数 (PGA) 均由减小段和增大段构成, 竖向地震动作用时只有增大段;在距洞口20 m范围内, 衬砌受地震惯性力的影响较大, 超过20 m之后, 衬砌上的惯性力作用在减弱.%In the seismic analysis of tunnel portal section, the influence of seismic input direction should be taken into account.The article used the method of numerical simulation to conduct a comparative analysis to the dynamic response of slope and lining of tunnel portal section in different directions of seismic input.The results show that the dynamic response of tunnel portal section is the largest under the transverse earthquake input, followed by the longitudinal input, and smallest when the vertical input is applied.Both PGD and PGA of slope are composed of the decreasing section and the increasing section when the seismic input is transverse and longitudinal, and there is only the increasing section when the seismic input is vertical.Lining is influenced greatly by seismic inertia force within the range of 20 meters from the entrance, however, the seismic inertia force will be weakened beyond the range of 20 meters.