牛头山黄土铁路隧道的地震稳定数值模拟分析

为了获得天平铁路土建一标段的牛头山黄土隧道结构的动力稳定安全系数,从而为该隧道的安全运营提供可靠保证。本文考虑混凝土隧道衬砌结构为弹塑性本构关系,围岩土体为理想弹塑性材料,采用有限元软件ANSYS和抗剪强度折减法,利用时程分析法进行牛头山黄土隧道的地震稳定性分析,获得了它的地震稳定安全系数,定量估计该隧道结构的地震动安全储备情况。数值算例结果表明:(1)地震作用会使得黄土隧道结构的安全系数降低;(2)塑性区最先出现在底脚以及拱顶,然后出现在曲墙两侧。因此,结构设计时应加大衬砌厚度,并对曲墙两侧和底脚塑性发展严重区采取构造措施加强。

Numerical Simulation Analysis of Earthquake Stability about the Niutou Shan Loess Railway Tunnel

To obtain dynamic stable safety factor of Niutou shan loess railway tunnel in the first bidding period of Tianping railway construction, in order to provide a reliable guarantee for safe operation of the tunnel. In this paper, considering the elastoplastic constitutive relation of the concrete lining structure and perfect elastoplastic material, and adopting the finite element software ANSYS and shear strength reduction method, the earthquake stability of Niutou shan loess railway tunnel is analyzed using time-history analysis, and the dynamic safety factor of the tunnel is obtained, and the loess tunnel seismic dynamic stability security reserve of the tunnel is estimated quantitatively. Numerical example result shows that: (1) the seismic action makes the loess tunnel structure safety factor decrease; (2) the plastic zone first appears at the foot and the vault, and then appears on both sides of the curved wall. Thus, the lining thickness should be increased during the structure design, and structural measures should be adopted on both sides of the curved wall and the bottom of plastic development zone.