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为了保证隧道施工和后期运行的安全,要选择出一个普遍适用于大断面矩形隧道的开挖方案。采用FLAC3D有限差分软件对3种不同的施工方案进行数值计算,对施工过程中隧道周围岩体位移、地表沉降以及周围岩体应力变化的计算结果进行对比分析,结果表明,采用先开挖隧道两侧岩体,后开挖隧道中部岩体的施工方案在应力集中程度和地表沉降方面比其余两种方案最大可降低41.3%和9.5%;隧道开挖过程中对地表沉降影响的范围大致为隧道跨度的5倍;浅埋大断面矩形隧道两侧岩体水平位移模式为向隧道外侧位移,与一般隧道不同。最后,优选出的施工方案将为大断面矩形隧道的实际施工提供参考。
In order to ensure the safety of the tunnel construction and the later operation, an excavation scheme universally applicable to the large-section rectangular tunnel should be selected. The FLAC3D finite difference software is used to calculate three different construction schemes. Comparing the calculation results of rock mass displacements, surface subsidence and stress changes of the surrounding rock mass around the tunnel during construction, the results show that the excavation tunnel Side rock mass and the rock mass in the middle of post-excavation tunnel are 41.3% and 9.5% less than the other two schemes in terms of stress concentration degree and surface subsidence. The range of influence on surface subsidence in tunnel excavation is roughly the tunnel 5 times of the span. The horizontal displacement of rock mass on both sides of shallow buried large cross-section rectangular tunnel is displaced to the outside of the tunnel, which is different from the general tunnel. Finally, the optimal construction scheme will provide a reference for the actual construction of large-section rectangular tunnel.