大断面公路隧道开挖数值模拟与监测研究

以大断面公路砂岩隧道——连湖隧道工程为依托,结合数值模拟对台阶法及CD法施工围岩应力及位移变化规律进行对比分析。结果表明,CD法开挖时拱顶下沉和水平收敛的累计位移相比两台阶法分别减少了27.8%和34.0%;围岩受力急剧增长阶段发生在洞室开挖前5 d;模拟台阶法、CD法施工时拱顶下沉和水平收敛的变形量分别比实测值小7.1%和11.8%、32.9%和41.8%;围岩整体受力呈先急剧增加后缓慢增加再趋于稳定的趋势,二衬受力稳定值分布呈中间小、两侧大的马鞍型,施工过程中需加强左右断面的监控量测工作。

Research on Numerical Simulation and Monitoring of Large Section Highway Tunnel Excavation

This paper takes Shilipu Tunnel,a large-section highway sandstone tunnel,as engineering background.Numerical analysis software was used to simulate the tunnel construction process.The stress and displacement changes of surrounding rock caused by the bench method and CD method were compared and analyzed with numerical simulation.The results show that the cumulative displacement and deformation of the tunnel vault subsidence and horizontal convergence using the CD method are reduced by 27.8%and 34.0%respectively compared with the bench method.The rapid growth stage of the surrounding rock force occurs in the first 5 days of the excavation.By simulating the bench method and the CD method,the simulative displacement of the vault subsidence and horizontal convergence are 7.1%and 11.8%,32.9%and 41.8%smaller than the measurements,respectively.The overall force on the surrounding rock increases sharply,then slowly increases,and finally tends to be stable.The stress distribution of the second lining force generally shows a saddleshaped distribution shape with a small middle and large sides.Therefore,it is necessary to strengthen the monitoring and measurement of the left and right sections.