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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。
The dynamic response of the circular lining tunnel and the orbit structure in the full space of saturated soil under the action of moving harmonic load is studied by analytical method. The infinite cylindrical shell is used to simulate the lining. The soil is modeled by the Biot saturated porous media theory and the Euler beam theory is used to simulate Rail, and floating plate to form a periodic two-layer composite beam unit. Combining the continuous force and displacement conditions at the track and the lining of the lining, the coupling between the track structure and the lining and the surrounding saturated soil is realized. The effects of load moving velocity and natural frequency on the displacement of track structure, the displacement of saturated soil and the pore pressure are analyzed by examples. The dynamic characteristics of continuous floating slab track and discrete floating slab track are contrasted. The results show that there is a parametric excitation in the response spectrum of the orbital structure and saturated soil due to the discontinuous floating plate during the loading period. When the natural frequency of the load approaches the natural frequency of the orbital structure, resonance occurs. Track structure and saturated soil displacement and pore pressure response have a greater impact; discrete floating plate track and continuous floating plate orbit dynamic characteristics are significantly different, when the load frequency close to the finite length of the floating plate to form the standing wave frequency, the second The corresponding free field response difference is obvious; increasing the lining thickness can significantly reduce the displacement response of saturated soil.