断层错动及地震作用下隧道力学特性研究

Research on Mechanical Characteristics of Tunnel under Fault Movement and Seismic

依托国外某穿越走滑断层的高速铁路隧道,利用FLAC3D建立三维有限元模型,通过在断层两侧施加强制位移,研究在走滑断层错动作用下的隧道衬砌力学特性,并基于此对隧道在地震波作用下的动力响应规律进行动力分析,最终得到依托隧道的抗错动及抗震加固长度。结果表明,在走滑断层错动作用及地震动作用下,衬砌内力及应力在断层破碎带与上下盘交界面处达到峰值,并随着监测断面沿轴线方向远离断层时逐渐趋于稳定。随着断层错动量的增加,衬砌内力与应力逐渐增加;随着输入地震波方向与隧道轴线夹角的增加,衬砌内力与应力逐渐减小。最终得出,断层错动0.1 m时,断层两侧隧道加固长度为3.7D(D为隧道内径);断层错动0.25 m时,隧道加固长度为4.5D;断层错动0.5 m时,隧道加固长度为5.2D。

This paper focuses on the mechanical characteristics of the tunnel lining under strike-slip fault movement by establishing a 3D finite element model with FLAC3 D and adding forced displacement. On this basis, the dynamic response rules of the tunnel to seismic are researched with the dynamic analysis method with reference to the the high speed railway tunnel through strike-slip fault zones in a foreign country. Finally, the reinforced length of the tunnel under fault movement and seismic is determined. The research results show that: the internal forces and stresses of the lining reaches the peak when the tunnel is located on the interface of the surrounding rock and the fault fracture zone, and gradually stabilizes with the monitoring section moving away from the fault zone along the tunnel axis. The internal forces and stresses of lining increases gradually with the increase of the fault displacement;the internal forces and stresses of lining decreases gradually with the increase of the angle between seismic direction and tunnel axis. It is concluded that the reinforced length is 3.7, 4.5 and 5.2 times of the inner diameter of the tunnel respectively, when the fault offset is 0.1 m, 0.25 m and 0.5 m.