大跨软岩隧道二衬合理支护时机的分析与优化

随着我国高速公路大规模的建设,新奥法的基本理念已经被广泛应用于大跨软岩隧道施工中,因此,支护时机的选择尤为重要。以集呼高速公路金盆湾隧道为例,应用大型通用软件ANSYS建立有限元模型,采用弹塑性方法及Drucker-Prager屈服准则,进行二维平面应变模拟。数值模拟CD法施工时不同荷载释放系数下的开挖与支护,通过分析隧道围岩受力状态、围岩变形、初期支护结构力学性能变化及现场监测结果,初步确定二次衬砌的最佳支护时机。

Simulation and Optimization of Supporting Time of Secondary Lining for Large-Span Soft Rock Tunnel

With large scale construction of highways in China, basic idea of new Austrian tunneling method has been widely applied in the large-span soft rock tunnel construction and selecting an optimum supporting time is particularly important. Combined with the bay tunnel in Jihu highway project, a finite element model by large general software ANSYS is established, two-dimensional plane strain numerical simulation to the large-span soft rock tunnel is carried out with elastic-plastic method and Drucker-Prager yield criterion. It numerically simulates excavation and support by CD construction method under different load release factor, by analysis of the variation of surrounding rock stress condition, deformation and its supporting structure mechanical properties and considering the results of in-situ monitoring to estimate the optimum supporting time of the secondary lining.