“土-岩”复合地层盾构始发井横通道开挖支护力学行为研究

Analysis of Mechanical Behaviors during Shield Launching Shaft Cross-Passage Construction in Soil/Rock Mixed Ground

结合长春地区特殊的"土-岩"复合地质情况,文章首先通过对横通道施工阶段地表及洞内沉降监测进行数据分析,总结出CRD工法施工过程中土层的沉降变形规律;然后采用有限元软件MIDAS/GTS分析横通道施工引起支护结构和上覆埋地管线的变形及受力情况,并与实测数据进行对比分析。结果表明:(1)1~4号导洞开挖对地表沉降贡献较大,占总沉降的74%;(2)掌子面开挖的影响范围约为其前后15 m;(3)初期支护中拱顶及底部仰拱Mises应力较大,且初期支护交接处均出现应力集中;(4)管线中部Mises应力最大,在距离中轴线约10 m的位置出现应力最低点。

Facing the special ＂soil/rock＂ mixed ground condition in the Changchun area, the monitoring data of ground surface settlement and the convergence deformation during cross-passage construction were analyzed, arid the settlement and deformation laws were obtained during the construction process using the CRD method. Then, a numerical simulation was conducted using MIDAS/GTS finite-element software to study the settlement, deformation and mechanical behaviors of the support structure and buried pipelines during cross-passage excavation. After a comparison with the measured data, some results were determined： 1） ground surface subsidence induced by the excavation of pilot tunnels 1-4 accounts for 74% of the total settlement; 2） the influence scope caused by tunnel face excavation is around 15 m ahead of and behind the face; 3） the Mises stress in the vault and invert of the primary support structure is high, and the stress concentration emerges at the junction of the primary support structure; and 4） the maximum Mises stress is in the middle of the pipelines with the lowest stress point being about 10 m away from the axis of the pipeline.