洞口段浅埋偏压隧道新型防护结构及其简化计算方法

针对现有洞口段浅埋偏压隧道支护结构在施工时所存在的容易坍塌、整体位移过大等问题，在充分发挥抗滑桩、锚索和管棚优点的基础上，利用交叉施工和分时注浆方法，提出一种洞口段浅埋偏压隧道新型防护结构。建立地形偏压下防护结构的简化分析模型，并利用M法对防护结构在地形偏压下的内力和位移进行求解；然后利用变形协调条件对结构的内力和位移进行修正，最终得出该新型结构在地形和施工偏压联合作用下的受力和变形状况。结合算例，对新型防护结构的内力和位移分布规律进行分析，并将计算结果与ADINA模拟结果进行对比，验证了简化计算方法的可靠性，为该新型结构的分析与设计提供了理论基础和依据。

New Protective Structure for Shallow-buried Bias Tunnel at Portal Section and Its Simplified Calculation Method

To address the problems of easy collapse and excessive displacement of the support structures of shallow-buried bias tunnels during construction of an existing tunnel section, a new protective structure for the shallow-buried bias tunnel at the portal section was proposed. The advantages of anti-slide piles, anchor cables, and pipe sheds were considered and utilized for the cross-construction. The simplified analysis model of the protective structure under terrain bias was established, and the internal force and displacement of the protective structure under terrain bias were solved using the M method. Then, the internal force and displacement of the structure under the combined action of terrain and construction bias were corrected and obtained by the deformation coordination condition. Combined with the example model, the internal force and displacement distributions of the new protective structure were analyzed. The reliability of the simplified calculation method was thus verified by comparing the calculation results and the ADINA simulation results, which provides a theoretical basis for the analysis and design of similar new structures.