中文摘要：

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。

英文摘要：

In order to guarantee the safety during tunnel construction and in later operation stage, an excavation scheme should be determined which is generally applicable for tunnel with large rectangular section. The FLAC 3D finite difference numerical analysis software is used to carry out numerical calculation for three different construction schemes. The displacement of surrounding rocks, surface settlement and stresses of surrounding rocks caused by different construction scheme are analyzed and compared. Results show that the excavation scheme that excavate firstly both sides surrounding rocks then to the middle is the best, the degree of stress concentration of surrounding rock and the surface settlement can be reduced by 41.3% and 9.5% ; the influence scope of tunnel excavation on ground surface settlement is 5 times of the tunnel span; different with the common tunnel, the horizontal displacement of side walls for the shallow covered urban tunnel with large rectangular section is outwards. Finally, the best construction scheme can provide reference for construction of tunnel with large rectangular section.