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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。
With the large-scale construction of the expressway in our country, the basic concept of the new Austrian law has been widely used in the construction of large-span soft-rock tunnels. Therefore, the choice of supporting timing is particularly important. Taking Jintanwan tunnel of Jueh-Hu Expressway as an example, a finite element model was established by using large-scale general software ANSYS. The two-dimensional plane strain simulation was carried out by elasto-plastic method and Drucker-Prager yield criterion. Numerical simulation of excavation and support of CD method under different load release factors during construction were carried out. By analyzing the stress state of surrounding rock, the deformation of surrounding rock, the mechanical properties of initial support structure and the monitoring results, Good support time.