依托郑西高铁高桥隧道小角度下穿既有南同蒲铁路施工实践，通过试验研究取得大断面黄土隧道台阶法双层支护体系的力学特性及施工技术关键，在砂质新黄土条件下成功解决埋深仅11 m的下穿运营铁路的超大断面（171 m²）隧道施工，对类似工程的设计与施工具有重要参考价值。

Relying on the construction under crossing the existed south Tongpu Railway with a small included angle at Gaoqiao tunnel of Zhengzhou-Xi’an high speed rail, carrying out the test and study, the mechanical characteristics and key construction techniques of the double-layer support system of large-section loess tunnels by benching method are acquired. It successfully resolved the construction difficulties of super-large-section tunnel (171m₂) under crossing the operating railway in the depth of only 11m under sandy neoloess, thus to have the significant reference for the design and construction of the similar engineering.