偏压大跨小净距公路隧道施工力学行为

为分析偏压大跨小净距隧道施工力学行为,采用FLAC3D有限差分数值模拟软件,针对偏压大跨小净距隧道在施工过程中的应力应变变化规律和施工方法比对、选择,开展现场监测数据对比论证与数值模拟计算分析。研究结果表明:由于偏压的影响,左线隧道的沉降、应力和受力均要大于右线隧道;开挖完成后左右线隧道拱顶和拱腰处的主应力会大幅度增加,造成隧道衬砌结构的剪应力也随之增大,同时也增大了两隧道间夹岩的主应力和剪应力,最终两隧道拱腰处应力集中明显;相比于左线隧道,右线隧道的开挖对左线隧道的弯矩影响更大,尤其是左线靠近右线隧道一侧拱腰的弯矩。其结果能够为偏压大跨小净距公路隧道的设计和施工提供了科学依据。

Mechanical behavior of large-span and small spacing road tunnel with biased pressure

In order to analyze the mechanical behavior of large-span and small spacing tunnel with biased pressure, the finite difference numerical simulation software FLAC3D was used to analyze the stress-strain evolution law and to select the construction method by comparing in situ monitoring data with numerical simulation results. The results showed that due to the influence of the biased pressure, the settlement and stress values of the left-line tunnel were larger than those of the right-line tunnel. The principal stress of the tunnel crown and arch waist increased greatly after the excavation, which would increase the shear stress of the tunnel lining structure,at the same time, the principal stress and shear stress of the middle surrounding rock increased. So the stress concentration occurred near the arch waist of the two tunnels. Compared with the change of the axial force of the left-line tunnel, the excavation of the right-line tunnel had a greater influence on the bending moment of the left-line tunnel, especially on the bending moment of the arch waist of left-line tunnel near the side of the right-line tunnel. The results provided a scientific basis for the design and construction of the large-span small spacing road tunnel with biased pressure.