以郑西客运专线阌乡隧道为依托工程，进行浅埋大跨黄土隧道长大管棚受力机制的研究。对隧道进入下穿高速公路前的管棚纵向变形进行现场监测，根据测试结果分析管棚在隧道开挖过程中的受力特性，得到浅埋黄土隧道长大管棚受力变形规律：掌子面前方约15 m处管棚开始受力，掌子面过后约15 m管棚的受力趋于稳定，管棚的纵向变形总体上呈凹槽形分布，掌子面处管棚受力最大。通过有限差分程序FLAC3D计算不同管棚参数条件下的施工方案，为隧道下穿段管棚工法及施工方案的优化设计提供理论依据，并在下穿段沉降监测中得到验证。

A series of research on mechanical behaviors of big pipe-roof in shallow large-span loess tunnel was made on Wenxiang Tunnel in Zhengzhou-Xi'an Special Passenger Railway. The longitudinal deformations of the pipe-roofs are monitored and the mechanical behaviors of the pipe-roofs are researched at the test section. The force-deformation law of big pipe roof in loess tunnel was obtained: in front of the excavating face about 15 m, the pipe roof started to bear the load; after the excavating face about 15 m,the load became stable; the longitudinal deformation of the whole pipe-roofs was groove-shaped distribution; the largest force of pipe-roofs was at the excavating face. The conclusions can provide reference for the design parameter optimization and the construction scheme selection of pipe-roofs and had been verified in the result of numerical analysis software FLAC3D and deformation monitoring.