地震SV波斜入射下沉管隧道的地震响应分析

在ABAQUS黏弹性人工边界时域波动方法的基础上,首先运用等效应力输入方法实现地震SV波倾斜入射,半空间算例验证该方法具有较好的计算精度,进而基于所建立的斜入射方法研究地震波斜入射对海河沉管隧道地震响应的影响。计算结果表明:SV波斜入射情况下,沉管隧道的地震响应规律与垂直入射时具有明显差异;随入射角增加,沉管隧道结构应力增大,应力较大点出现在沉管隧道的四个角点及隔墙与底板、顶板的连接处,其中中隔墙为最薄弱点;随入射角增加,侧墙和隔墙的相对最大水平位移增大,其中中隔墙位移最大;随入射角增加,沉管隧道结构竖向加速度峰值明显增大。因此在沉管隧道结构抗震设计中应考虑地震波斜入射的影响。

Seismic Response Analysis of Immersed Tunnel underOblique Incidence of Seismic SV Wave

With development over time, the immersed tunnel is becoming increasingly important. This tunnel is generally built in underwater environments and requires special considerations with respect to its design and safety factors. Researchers around the globe have conducted many studies on this type of structure and have found that it can be affected by the liquefaction of the foundation and hydrodynamic pressure due to earthquake, the interaction between soils and structures, and the oblique incidence of seismic waves. In this paper, we use the time-domain wave method coupled with a viscous-spring artificial boundary condition and the equivalent stress input method to obtain the oblique incidence of shear-vertical (SV) waves. The half-space numerical results demonstrate this method to have good precision. We then applied the proposed method to investigate the seismic response of the Haihe immersed tunnel subjected to the oblique incidence of seismic waves. The simulation results show that the dynamic responses of the immersed tunnel subjected to the action of obliquely incident seismic waves clearly differ from those due to vertically incident seismic SV waves. With increases in the incident angle, the stress on the immersed tunnel increases, and a larger stress point appears in the four corners of the tunnel and in the connection between the partition wall and the bottom plate and the roof, with the middle partition wall being the weakest point. With increases in the incident angle, the relative maximum horizontal displacements of the side wall and partition wall increase, and the displacement of the middle partition wall is the greatest. With increases in the incident angle, the vertical acceleration rate of the tunnel structure increases significantly. Therefore, seismic research of immersed tunnel structures should consider the effect of obliquely incident seismic waves.