超大断面隧道双侧壁导坑法开挖步序优化

发布时间：2018-06-12 05:50

本文选题：浅埋扁平超大断面隧道 + 围岩应力　；参考：《河南科技大学学报(自然科学版)》2017年04期

【摘要】：重庆市轨道交通5号线1期3标段为富水浅埋扁平超大断面隧道工程,采用9步双侧壁导坑法中的对称开挖步序施工。应用MIDAS-GTS软件建立隧道三维有限元模型,计算了3种不同开挖步序条件下地表沉降、围岩变形和支护结构受力情况,并将计算结果与现场监测数据进行了对比验证。验证结果表明:扁平超大断面隧道拱顶区域受力作用面较大,拱顶区域围岩及喷混支护应力较大,拱顶稳定性较低,拱脚应力集中。施工阶段隧道结构对横向变形较为敏感,3种开挖步序拱脚水平收敛值曲线随施工步序呈现多台阶变化;中隔墙核心土拆除时,水平收敛值及拱顶沉降值曲线出现突变,该阶段应增大监测频率。对3种施工步序进行了数值模拟,提出了本工程地质条件下大跨扁平隧道施工的合理步序。
[Abstract]:The third section of No. 1 phase of Chongqing Rail Transit Line is a shallow, flat and super-section tunnel project with rich water. The symmetrical excavation sequence of 9 steps double-sidewall diversion pit method is used to construct the tunnel. The 3D finite element model of tunnel is established by using MIDAS-GTS software. The ground subsidence, surrounding rock deformation and stress of supporting structure are calculated under three different excavation sequence conditions, and the calculated results are compared with field monitoring data. The test results show that the stress surface of the arch roof of the flat super-large section tunnel is large, the surrounding rock and shotcrete support stress in the arch top area is larger, the stability of the arch roof is low, and the stress concentration of the arch foot is very low. In the construction stage, the horizontal convergence curve of the arch foot of three kinds of excavation step is more sensitive to the transverse deformation, and the horizontal convergence value and the settlement curve of the arch roof are abrupt when the core soil of the middle partition wall is removed, and the horizontal convergence curve of the arch foot changes with the construction step sequence. The monitoring frequency should be increased at this stage. The numerical simulation of three kinds of construction sequence is carried out, and the reasonable construction sequence of long span flat tunnel under this engineering geological condition is put forward.
【作者单位】：中铁隧道集团勘测设计研究院;河南科技大学土木工程学院;中铁重庆地铁建设指挥部;
【基金】：国家自然科学基金项目(11402077) 河南省科技厅产学研合作基金项目(2015HNCXY011)
【分类号】：U455.4

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