基于数值模拟的北京地区地下道路立交隧道围岩变形分析

Numerical analysis of the surrounding ground deformation in interchange tunnel for underground road in Beijing

城市地下道路立交隧道施工过程中围岩变形分析是工程建设中的核心问题。依托北京城市地下道路工程,采用城区地质条件分层概化方法、三维数值模拟方法分析了临时仰拱台阶法(台阶法)、中隔壁法(CD法)、交叉中隔壁法(CRD法)和双侧壁导坑法(双侧壁法)施工影响下的立交隧道地表沉降、洞周变形和塑性区分布特征,明确了立交区域上下层隧道施工的影响规律。研究发现,立交区域同时受到了上下层隧道施工的影响,在地表形成椭球形的沉降盆,在洞周出现了较大的差异沉降;在地表地层和洞周拱脚、拱肩截面的"X"形区域出现了较为集中的破坏区;CRD法和双侧壁法在控制立交隧道地层变形和破坏方面具有明显优势。研究成果可为北京城市地下道路立交隧道设计、施工决策制定提供参考。

Analysis of the surrounding ground deformation is the key problems in the design and construction of interchange tunnels for the underground road in Beijing. Based on the urban underground road construction in Beijing,with the hierarchical generalized model of geological conditions and three dimensional numerical simulation analyzed the surface settlement,tunnel deformation and plastic zone distribution of interchange tunnel by bench method,center diagram( CD),cross diagram( CRD) and double side drift method,cleared the influence law on the underlying interchange area in tunnel construction. The results can be shown as follows. The interchange area was interrupted by above and lower tunnel construction. Ellipsoidal surface formed. Meanwhile,there is a greater differential settlement in the surrounding. In the 'X'shaped area of the surface layer,the arch foot and spandrel appeared more concentrated damage area. There are obvious advantages in controlling ground deformation and the damage of interchange tunnels by CRD and double side drift method. The results can be a reference for the relevant design and construction of interchange tunnels in the underground road in Beijing.