【摘要】 本文用有限元法对某黄土隧道进行了列车振动响应数定分析。文中提出一种人工激振力以模拟列车竖向动荷载,并采用Newmark隐式时间积分法求解结构体系的二阶运动微分方程组。对各种材料均采用弹塑性本构关系和摩尔-库伦屈服准则,所有超过屈服点的应力均予以调整使之回到屈服面上。分析表明隧道衬砌将主要承受拉应力作用,且最大拉应力发生在最大跨度偏下的边墙内表面上。对体系的自振特性也进行了探讨,算得的最小特征值与动力分析中所得到的自振周期吻合良好。更多还原

【Abstract】 The finite element method was applied here to the dynamic deterministic ana-Lysis of responses to passing trains of a tunnel built in loess soil. An artificialexciting force was posed to simulate the vertical dynamic force of the passingtrains. The Newmark’s predictor-corrector implicit time integration algorithm wasfollowed in solving the second order differential equations of motion of thesystem.,An elasto-plastic constitutive model incoriportating Mohr-Coulomb’s failureeriterion was adopted with post-yield-stresses adjusted back to the yield surface.The tunnel lining would mainly sustain tensile stresses which were most criticalin the inner surface of the wall near and below the maximutn span. Pree vibrationcharacteristics of the system were estimated with the lowest and highesteigen values evaluated and, relevent mode shape were presented. The period of freevibration of the system obtained in the dynamie analysis after the passing of thetrains was about identical to the lowest eigen value calculated.更多还原