严重偏压地形下隧道半明半暗进洞技术探讨

山岭高速公路沿河、傍山展线时，部分隧道洞口往往存在地形偏压，从而导致隧道进洞困难，通过某高速公路1座隧道洞口的工程实例，探讨地形偏压严重时隧道半明半暗进洞的技术问题，提出隧道半明半暗进洞方案，并利用有限元数值模拟分析隧道进洞过程中围岩及支护的力学状态，总结半明半暗进洞方案的注意事项，为工程实施提供理论支撑。目前该隧道洞口已安全顺利进洞，未发生工程病害，可为同类工程参考。

Discussion on Construction Technology for Half-buried Tunnel Portal Section in Extremely Asymmetrically-Loaded Condition

In case highways in mountainous areas are routed along rivers and/or along mountain sides, some of the tunnel portals are located in asymmetrical-loaded conditions, which results in great difficulties to the construction of the portal sections. The scheme of half-buried portal section in extremely asymmetrically-loaded conditions is proposed and studied, with the portal section of a highway tunnel as an example. The stress conditions of the surrounding rock mass and the reinforcement structure are analyzed by FEM and the key points of the half-buried portal section scheme are summarized, which provides theoretical support for the execution of the works. So far the construction of the tunnel portal section has been successfully completed and no engineering diseases have occurred. The paper can be served as reference for similar projects in the future.