不同地震动输入下山岭隧道洞口段抗震性能研究

Study on Seismic Performance of Mountain Tunnel Portal Section under Different Seismic Motion Input

为研究不同方向地震动输入下山岭隧道洞口段的抗震性能,通过建立有限元数值模型分析隧道洞口段的动力响应特征及二次衬砌的安全性能。结果表明:最大位移在Y向地震动输入时最大,Z向次之,X向最小,最大值出现在拱顶处,最大加速度和最大主应力在X向最大,Y向次之,Z向最小;在不同地震动输入下,隧道洞口处最大主应力变化幅度最大,说明隧道洞口段受地震影响较大,是抗震的薄弱环节;隧道洞口段各部位的轴力分布较均匀,整个隧道处于受拉状态,安全系数满足规范要求,但在拱顶和左、右拱脚处安全系数已接近限值,需要在隧道施工中采取一定的加固措施,以保证隧道的稳定性。

In order to study the seismic performance of tunnel mountain portal section in different directions,the dynamic response characteristics of tunnel entrance and the safety performance of secondary lining are analyzed by establishing a finite element numerical model.The research results show that:The maximum displacement value is seismic motion input in Y direction,the mediant in Z direction,the minimum in X direction.The maximum value appears at the vault,the maximum acceleration and principal stress is in X direction,the mediant is in Y direction,and the minimum is in Z direction.Under different ground motion input,the maximum principal stress at the tunnel portal changes the most,which shows that the tunnel portal section is greatly affected by the earthquake and is the weak part of the earthquake resistance.The axial force is evenly distributed in all parts of the tunnel,the whole tunnel is in tension state,and the safety factors of all parts of the tunnel meet the requirements of the code.However,the safety factors at the arch crown,left and right arch feet are close to the limit value,it is necessary to adopt certain reinforcement measures in the tunnel construction to ensure the stability of the tunnel.