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针对西安地铁留核心土、上下半洞开挖、超前小导管注浆加固与水平钢撑锁脚的钢拱架和挂网喷层支护的饱和黄土隧道,根据现场地面沉降监测数据,分析了隧道右线、左线掌子面间隔30m开挖过程中洞顶地表沉降变形的历时变化规律,以及左、右线单洞沉降槽和双线沉降槽的分布特征。结果表明,洞顶地表沉降变形可以划分为初期沉降变形、右线开挖主变形、左线开挖主变形及沉降变形稳定4个阶段;左、右线单洞沉降槽和双线沉降槽均可用高斯分布曲线拟合。基于沉降槽Peck公式及O’Reilly和New最大沉降与隧道埋深的关系,得到了饱和黄土隧道单洞与双洞地面沉降槽的宽度和最大沉降,以及右、左线隧道先后开挖单洞的沉降槽宽度比和最大沉降比。考虑双线隧道洞间距、左右洞先后开挖地层松动相互影响以及围岩饱和黄土固结变形的影响,提出了一种饱和黄土隧道双洞开挖施工引起地表沉降的预测模型,验证了该预测模型应用的可靠性。
According to the core soil of Xi’an Subway, the excavation of the upper and lower half-holes, the advancement of small conduit grouting reinforcement and the horizontal arch-supported steel arch and the saturated loess tunnel supported by the gob sprayed layer, the tunnels are analyzed according to the monitoring data of on-site land subsidence The variation of settlement and deformation of the top of the tunnel roof during the 30m excavation with the left and right lines and the distribution characteristics of the single-hole settling tank and the double-line settling tank in the left and right lines. The results show that the deformation of the top of the tunnel can be divided into four types: initial settlement, main deformation of right excavation, main deformation of left excavation and stability of settlement. Available Gaussian distribution curve fitting. Based on the Peck formula of settling tank and the relationship between the maximum settlement of O’Reilly and New and the depth of tunnel, the width and maximum settlement of single-hole and double-hole ground settlement grooves in saturated loess tunnel are obtained, Settling tank width ratio and maximum settlement ratio. Considering the influence of two-lane tunnel spacing, the loosening interaction between the two adjacent tunnels and the consolidation and deformation of saturated loess surrounding rock, a prediction model of surface subsidence caused by double-hole excavation in saturated loess tunnel is proposed. The prediction model Application reliability.