Abstract: Considering the physical and mechanical parameters of loess and the sequence of the excavation，the longitudinal and latitudinal layouts of bolts were numerical analyzed with the Duncan—Chang constitutive model． Based on Xi’an Metro line 2 tunnel’s actual design information and the data of the underground exploration，the ground settlement and bolt force characteristics were analyzed with a finite element software MIDAS when bolt’s length and spacing were different． Moreover， the longitudinal interval and latitudinal intensive location of bolts were discussed． The numerical results show that the ground settlement becomes smaller with the increase of the bolt length． However，the ground settlement will trend to a constant when the bolt reaches a certain value; the ground settlement becomes bigger when the longitudinal interval of bolt is uneven; In addition，it is useful for ground settlement when bolts are put intensively on tunnel waist．

Key words: subway, tunnel, bolt, finite element analysis, settlement

摘要： 根据黄土地层不同土的物理力学参数，应用邓肯—张本构模型，在地铁隧道开挖施工过程中，对支护锚杆系统 沿隧道纵向和横向的不同分布形式进行有限元数值计算。应用有限元软件MIDAS，根据西安地铁2号线隧道的相 关土性和设计资料，对比了锚杆长度和锚杆纵向间距对地层沉降和锚杆受力特征的影响;探讨了锚杆纵向间距的疏 密布置以及横向加密的位置。分析表明随着锚杆长度的增加地层沉降减小，当锚杆长度大于一定值后沉降变化幅 度降低;当锚杆纵向布置疏密不均时，沉降量较大;在隧道腰部加密锚杆可控制地表沉降。

关键词: 地铁, 隧道, 锚杆, 有限元分析, 沉降