特大跨度公路隧道上方卸载对隧道影响分析

Analysis on Influence of Unloading above the Extra Large-Span Highway Tunnel on the Tunnel

为研究扁平特大跨度公路隧道上方路堑开挖卸载对隧道的影响,以厦门翔安机场高速公路内厝互通立交工程为例,建立三维数值模型结合现场实测,分析上部土方开挖对隧道的影响,以及隧道形状、上覆土方开挖重心位置等因素的敏感性。研究表明:下卧隧道与道路开挖处地表位移最大、变形最大;在开挖过程中,边坡地表和隧道最大位移是动态变化的,隧道变形指向地表最大位移位置,随之偏转;无论从变形规律还是从受力规律进行对比,扁平形隧道受上覆土体开挖影响显著,设计中应加强对扁平隧道侧壁与拱脚的验算;对于非水平地形,不能简单根据残留埋深比来判断影响度。

To study the influence of cutting excavation and unloading above flat super longspan highway tunnel on the tunnel,taking Neicuo interchange project of Xiamen Xiang'an Airport Expressway as an example,a three-dimensional numerical model is established.Combined with the field measurement,the influence of upper earthwork excavation on the tunnel and the sensitivity of tunnel shape,overlying earthwork excavation center of gravity and other factors are analyzed.The research shows that the surface displacement and deformation of the underground tunnel and road excavation are the largest.In the process of excavation,the maximum displacement of slope surface and tunnel changes dynamically,and the tunnel deformation points to the position of maximum displacement of surface and deflects accordingly.No matter from the deformation law or the stress law,the flat tunnel is significantly affected by the excavation of the overlying soil,and the checking calculation of the side wall and arch foot of the flat tunnel should be strengthened in the design.For non-horizontal terrain,the influence degree cannot be judged simply according to the residual buried depth ratio.