中文摘要：

采用解析法研究了移动简谐荷载作用下饱和土全空间中圆形衬砌隧道和轨道结构的动力响应,用无限长圆柱壳模拟衬砌,用Biot饱和多孔介质理论模拟土体,用Euler梁理论模拟钢轨、浮置板并组成周期性的两层叠合梁单元,结合轨道与衬砌仰拱处的力和位移连续条件,实现轨道结构与衬砌及周围饱和土体的耦合。通过算例分析了荷载移动速度、自振频率对轨道结构位移、饱和土体位移及孔压的影响,对比了连续浮置板轨道和离散浮置板轨道的动力特性。结果表明：离散浮置板轨道情形下,轨道结构和饱和土体响应频谱中存在由荷载周期通过不连续浮置板而引发的参数激励;荷载自振频率接近轨道结构固有频率时产生共振,对轨道结构和饱和土位移、孔压响应均有较大影响;离散浮置板轨道和连续浮置板轨道动力特性有显著差异,当荷载频率接近有限长浮置板形成驻波的频率时,二者对应的自由场响应区别明显;增大衬砌厚度可以显著减小饱和土位移响应。

英文摘要：

Dynamic responses of the rail structure and underground railway tunnel in the saturated soil under moving harmonic load are investigated by using the analytical method. The tunnel is simulated as a thin cylindrical shell with infinite length, and the soil is modeled as a saturated poroelastic medium using the Biot＇s theory. The infinite track with periodic double beam units is formulated as a periodic structure. The tracks and soil medium are coupled by the force and displacement compatibility conditions at the tunnel invert. The effects of load velocity and external frequency on track responses and displacements and pore pressure of saturated soil are investigated. The dynamic characteristics of floating slab tracks with discontinuous and continuous slabs are analyzed. It is found that there exists a parametric excitation in the spectra of track and soil responses due to the moving load periodically passing through the discontinuous slabs. Resonance phenomenon occurs when the external frequency of load is equal to the natural frequency of the tracks. The dynamic characteristics of floating slab tracks with discontinuous and continuous slabs have significant difference. The displacements and pore pressures of saturated soil will be amplified at the natural frequency arising from the standing waves propagating in the discontinuous slabs. The displacements of the saturated soil can be effectively reduced by increasing the tunnel thickness.