暗挖隧道穿越杂填土地层数值模拟研究

Numerical Simulation of a Mined Tunnel Through Mixed Fill Stratum

以西安市地铁8号线某标段暗挖隧道为背景,采用FLAC3D软件建立暗挖隧道穿越杂填土地层三维数值计算模型,并分析了围岩应力和变形、衬砌结构应力和变形以及地表变形特性。研究结果表明,围岩应力呈层状分布,埋深越大应力越大,在隧道洞径约1倍范围内区域为隧道开挖扰动区;暗挖隧道开挖时,围岩影响范围和变形逐渐增大并趋于稳定;衬砌结构两侧壁以及拱顶有应力集中和扩散现象,表现为压应力和拉应力。隧道侧壁水平变形最大,竖向变形拱顶表现为沉降,拱底表现为隆起;隧道中轴线处地表水平变形为零,呈中心对称分布;隧道中轴线处地表竖向变形最大,呈轴对称分布。相关结论可为类似暗挖隧道施工提供参考。

Based on a mined section of Xi’an metro line 8,a 3D numerical calculation model of the mined tunnel through mixed fill stratum is established by FLAC3D.Then the stress and deformation of surrounding rock,stress and deformation of lining structure and surface deformation are analyzed.The results show that the stress of surrounding rock is distributed in layers and increased with buried depth.The tunnel excavation disturbance area is within about 1 time of tunnel diameter;When the mined tunnel is excavated,the influence range and deformation of surrounding rock gradually increase and becomes stable;The stress in both sides of lining structure and vault are concentrated and diffused,showing compressive stress and tensile stress.The horizontal deformation of the tunnel side wall is the greatest,the vertical deformation shows settlement in vault and uplift at the arch bottom;The horizontal deformation of the surface at the central axis of the tunnel is zero,which has a central symmetric distribution;The vertical deformation of the surface is the greatest at the central axis,which has an axisymmetric distribution.The relevant conclusions can provide reference for the construction of similar mined tunnels.