为提高大断面黄土隧道关键部位的施工安全，通过监测数据分析，总结宝兰客专14标多个三岔口的变形规律，指出主隧道中台阶开挖和仰拱浇筑分别是变形发展和变形控制的关键时期，由此预测了古城岭隧道3#斜井三岔口的最大变形，并优化了开挖方法，最终较好地控制了变形。

The regularity of the deformation of the junction sections of tunnels in No. 14 bid section of BaojiLanzhou passenger dedicated line is studied on basis of the monitoring results, so as to improve the construction safety of critical positions of large crosssection loess tunnels. It is concluded that the intermediate bench excavation and the invert casting are critical points in terms of deformation development and deformation control. Furthermore, the maximum deformation of the junction section of No. 3 inclined shaft of Guchengling tunnel is predicted on basis of the study results, and the excavation method is optimized accordingly. In the end, the deformation of the mentioned junction section has been well controlled. 