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以典型城市土岩复合地层中的某地铁CRD(交叉中隔壁法)隧道为依托,通过分析洞内、外变形监测数据,总结变形规律,对该隧道风险进行有效控制。研究结果表明:洞内、外变形量的60%以上是由上2层导洞开挖引起的;隧道开挖引起的地表沉降槽特征较为明显,地表最大沉降点位于隧道中心线上方偏左;隧道掌子面开挖的横向影响明显,范围约为60m。洞内变形监测的分析指标以拱顶沉降为主,水平收敛为辅;拱顶下沉曲线分段组成,总体呈台阶状下降。综合变形监测分析和施工经验认为:施工中应着重控制上2层导洞初期支护结构的及时闭合;相邻导洞掌子面间距控制在15~20m;台阶长度控制在5m以内,及时封闭仰拱,闭合成环,可有效地控制洞内、外变形和保证初期支护结构稳定性。
Based on the CRD tunnel in a typical urban earth-rock compound stratum, the tunnel risk is effectively controlled by analyzing the deformation monitoring data inside and outside the tunnel and summarizing the deformation rules. The results show that more than 60% of the deformation inside and outside of the tunnel is caused by the excavation of the upper two-level guide tunnels. The characteristics of the surface sedimentation tank caused by tunnel excavation are obvious. The maximum settlement point of the surface is located above the centerline of the tunnel. Excavation of the face of the horizontal impact of the obvious, the range of about 60m. The analysis indicators of deformation monitoring in the cave mainly consist of vault settlement and horizontal convergence, while the curve of vault settlement is subdivided into segments, which are generally stepped down. Comprehensive deformation monitoring and analysis and construction experience that: the construction should focus on the control of the initial support structure on the two-tier closure of the timely closure of the tunnel; Adjacent guide tunnel control surface spacing of 15 ~ 20m; step length control within 5m, timely closure Inverted arch, closed loop, which can effectively control the inside and outside the hole deformation and to ensure the stability of the initial support structure.