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为研究地铁列车运行引起的轨道系统及饱和土体动力响应问题,建立地铁列车–轨道结构–衬砌–饱和土体耦合分析模型,其中列车荷载用一系列符合列车几何尺寸的移动常荷载或移动简谐荷载模拟,轨道结构中的钢轨和浮置板简化为无限长弹性Euler梁。基于弹性理论和Biot多孔介质理论,采用2.5维有限元法分别模拟衬砌和饱和土体,结合轨道与衬砌仰拱处的力和位移连续条件,实现浮置板轨道系统与衬砌及周围饱和土体的耦合,并通过快速Fourier逆变换(IFFT)进行波数展开获得三维时域–空间域内的动力响应。研究结果表明,随着常荷载移动速度和移动简谐荷载自振频率的提高,地表振动水平显著增大;移动常荷载产生的地表响应最大值在荷载正上方,其空间衰减率保持恒定;移动简谐荷载产生的地基振动大于移动常荷载产生的地基振动,响应最大值在列车运行线路两侧一定范围内;在移动简谐荷载作用下,钢轨速度谱与地表速度谱分布在以简谐荷载自振频率为中心的一段范围内。
In order to study the orbit system and the dynamic response of saturated soil due to subway train operation, a coupled model of subway train-track structure-lining-saturated soil is established, in which the train load is simulated with a series of moving normal loads or moving profiles Harmonic load simulation, rail structures and floating plates in orbital structures simplify as infinitely long elastic Euler beams. Based on the theory of elasticity and Biot porous media, 2.5-D finite element method is used to simulate the lining and saturated soil respectively. Combining with the continuous force and displacement conditions at the track and the lining of the lining, the floating slab track system and the surrounding saturated soil And the wave number expansion through fast Fourier inverse transform (IFFT) to obtain the dynamic response in the three-dimensional time-space domain. The results show that with the increase of the normal moving velocity and the natural frequency of the moving harmonic load, the vibrational level of the ground surface increases significantly. The maximum of the surface response caused by the moving normal load is directly above the load, and the spatial attenuation rate remains constant. The vibration of foundation caused by the simple harmonic load is larger than that of the foundation caused by the frequent moving loads and the response maximum is within a certain range on both sides of the train running line; under the action of moving simple harmonic load, Self-vibration frequency as the center of a range.