浅埋大断面隧道施工工法优化分析

为了探索适合青岛胶州湾海底隧道陆域大断面段施工过程中的最合理施工工法,采用三维有限差分软件FLAC3D对4种常用施工工法进行数值计算优化分析,分析结果表明:双侧壁导坑法即眼镜法对地表沉降、洞周收敛和围岩稳定的影响方面要优于其他工法,而CD法施工主要对衬砌安全方面效果最佳。在实际施工过程中,综合考虑施工工期、进度、隧道埋深、洞径等,选择最佳施工工法。由于青岛海底隧道陆域大断面段隧道跨度较大,净空高,开挖台阶也高,致使钢支撑质量较大,安装困难,不宜使用CD法,最终确定选择双侧壁导坑法施工。通过实际工程验证,双侧壁导坑法在青岛胶州湾海底隧道陆域大断面段取得了显著的社会、经济效益,为今后类似工程对于该种工法的应用起到了很好的借鉴和指导作用。

OPTIMIZATION ANALYSIS OF CONSTRUCTION METHOD FOR SHALLOW-BURIED TUNNEL WITH LARGE SECTION

In order to find the most reasonable construction method for the Qingdao Jiaozhou Bay subsea tunnel with large section in land area,numerical simulation for the four kinds of common construction methods had been made by three-dimension finite differential software FLAC3D.The analytical results indicate that the double side heading method is better in the surface settlement,tunnel deformation and stability of surrounding rock than the other three methods.The DC construction method is more beneficial to the lining safety than the others.In the actual process of construction,it should be comprehensively considered lots of the factors including the construction period,schedule,tunnel depth,tunnel diameter and so on in the selection of construction method.It’s difficult to install the steel support because of the big span,high clearance and bench in Qingdao subsea tunnel with large section in land area.The CD method should not be used in the construction and the double side heading method is the best selection taking into account all the factors.The double side heading method has achieved significant social and economic benefits in the Qingdao Jiaozhou Bay subsea tunnel with large section in land area and will play a very good reference and guidance for similar projects in the future.