复杂条件下隧道支护结构稳定性分析

以方斗山隧道为研究对象，建立三维有限元数值分析模型，模拟分析了隧道支护结构的稳定性。以距离隧道洞口10 m处断面支护结构为例，分析了该断面初次支护和二次衬砌的水平应力、竖向应力、竖向位移、锚杆轴力及支护结构破坏域等随掌子面推进的变化规律，并对该断面支护结构特征点的稳定性进行追踪研究。研究结果表明，当掌子面与断面间距离小于30 m左右时，随着掌子面的推进，支护结构应力及位移等均有一定程度的增长，其后支护结构应力及位移基本收敛，且收敛值均较小，表明支护结构是稳定的。对隧道初次支护应力及锚杆轴力的现场监测结果及数值模拟结果进行对比分析，结果表明，数值模拟与现场监测结果基本一致。

Stability analysis of tunnel supporting structure under complex condition

Taking Fangdoushan tunnel for example, the 3D finite element model is built; and the stability of tunnel supporting structure is simulated and analyzed. The horizontal stresses, vertical stresses and displacement, anchor bar axial forces and the failure fields of the section which distance to the hole is about 10 m are analyzed; and the characteristic points of the section on the supporting structure is studied too. The results show that the stresses and displacements increase when the distance between the section and heading face are less than 30 m; after that, the stresses and displacements is convergent; and the increments are small. All of these show that the supporting structure is stable. The numerical simulation results of primary support stress and axial force of anchor bar are compared with the monitored results, from which it can be known that they are consistent basically.