新建铁路路基对下卧公路隧道的影响

为研究新建铁路挖方路基对既有公路隧道的影响,以某铁路客运专线路基上跨某高速公路隧道为依托,通过建立三维有限元模型,分析了开挖过程及运营时列车静载作用下公路隧道结构位移和内力的变化规律。结果表明,随着路堑边坡逐级开挖卸载的进行,隧道结构在竖直方向发生隆起,离铁路路基的位置越近,变形越大;埋深越小,衬砌内力受路堑开挖影响越明显。运营阶段考虑列车荷载时,隧道隆起量有所减少。采用荷载结构法对二衬结构进行内力计算,拱顶处安全系数仅为3.9。针对影响,研究提出施工建议,为同类工程提供相应参考。

Study on Influence of New Railway Subgrade on Underlying Highway Tunnel

To study the influence of newly excavated roadbed on existing highway tunnels,being based on the project of subgrade of Ganzhou-Shenzhen Passenger Railway overpassing Shishan Tunnel,a 3D finite-element model has been built.The structural displacement and internal force variation of Shishan Tunnel have been analyzed during excavation and operation stage.The results have shown that with the progress of excavation and unloading step by step,the tunnel structure rises in the vertical direction,with more obvious deformation encountered when being closer to the railway subgrade,with more obvious influence of excavation on the internal force of lining when the buried depth being smaller.While for the period of operation,the uplift of tunnel would be slightly reduced when train load is considered.The internal force of secondary lining structure has been calculated through Load-Structure Method,and the safety factor at the vault is only 3.9.Suggestions on construction have been put forward through relevant impact studies which could provide corresponding references for similar projects.