浅埋偏压地形和软弱围岩2大因素同时出现在隧道洞口时,施工方案应事先考虑并配合有力技术措施,因措施不力掘进后初支严重变形下沉再来处理,不仅费时费力,影响工程质量和进度,也不利于施工安全。本文介绍大乘山隧道进口段掘进后,初期支护严重变形产生的原因和处理方案。 Shallow buried bias topography and weak surrounding rock two major factors simultaneously appear in the tunnel entrance, the construction program should be considered in advance and with strong technical measures, due to poor measures after boring the initial branch serious deformation sink again to deal with, not only time-consuming and labor-intensive, affecting the project Quality and progress, but also not conducive to construction safety. This article describes the reasons for the severe deformation of the initial support and the treatment plan after the excavation of the entrance section of the Mt.