门源MS6.9地震中大梁隧道地震动响应分析

Seismic response analysis of the Daliang tunnel during the Menyuan MS6.9 earthquake

摘要:

2022年1月8日,青海省门源县发生M_S6.9地震,造成震中附近的兰新高铁大梁隧道受损,导致高铁长时停运。文章通过建立二维平面应变模型,加载双向门源波进行动力时程分析,得到了大梁隧道的地震动响应结果,并对模型在震后的受力变形及震害特征进行详细分析。结果表明:在门源波双向加载下,大梁隧道的地震动响应受水平地震荷载影响很大;沿着y轴正向,隧道的截面形状对纵向位移和加速度的地震动响应有加强作用;拱顶处地震动响应最大,其竖向及横向地震动响应加速度分别为5.206 4 m/s²、4.534 8 m/s²,竖向及横向位移分别为7.070 9 cm、0.641 5 cm;拱底处地震动响应最小,其竖向及横向地震动响应加速度分别为3.287 6 m/s²、4.511 2 m/s²,竖向及横向位移分别为4.851 6 cm、0.625 2 cm;拱肩、拱脚处存在明显的应力集中现象,拱顶、拱底、拱肩及拱脚处内力的受力形式发生变化,但是衬砌应力和内力的极值均发生在拱腰及拱脚处,说明拱腰及拱脚处为震害严重区,震后修复时应重点关注。

Abstract:

On January 8, 2022, an M_S6.9 earthquake occurred in Menyuan County, Qinghai Province. The earthquake caused damage to the Daliang tunnel of the Lanzhou-Xinjiang high-speed railway near the epicenter, resulting in a long-term shutdown of the high-speed railroad. In this study, a two-dimensional plane strain model was established to conduct a dynamic time-history analysis under the loading of bidirectional Menyuan seismic waves. The seismic response results of the Daliang tunnel were obtained, and the deformation and seismic damage characteristics of the model after the earthquake were analyzed in detail. The results show that the seismic response of the Daliang Tunnel was substantially affected by the horizontal seismic load under the bidirectional loading of Menyuan seismic waves. The cross-sectional shape of the tunnel strengthened the seismic responses of vertical displacement and acceleration along the y-axis. The largest seismic responses were observed in the tunnel vault. The vertical and horizontal seismic accelerations were 5.206 4 and 4.534 8 m/s², respectively. The vertical and horizontal displacements were 7.070 9 and 0.641 5 cm, respectively. The smallest seismic responses were detected at the arch bottom. The vertical and horizontal seismic accelerations were 3.287 6 and 4.511 2 m/s², respectively. The vertical and horizontal displacements reached 4.851 6 and 0.625 2 cm, respectively. An evident stress concentration occurred at the spandrel and arch foot, and the stress forms of internal forces changed at the vault, arch bottom, spandrel, and arch foot. However, the extreme values of stress and internal force of lining occurred in the arch waist and arch foot, indicating that these areas are severely damaged by earthquakes and should be given special attention during repair after earthquakes.