浅埋偏压隧道洞口施工技术及稳定性分析研究

Research on construction technique and stability analysis of outlet in shallow tunnel under unsymmetrical pressure

龙潭隧道是沪—蓉高速公路工程的控制性工程。地质条件复杂,集浅埋、偏压、涌水、涌泥、岩爆等地质问题于一身,是典型的复杂条件下的长大公路隧道。隧道洞口段处在浅埋偏压段时,施工难度相当大。从隧道开挖与支护的安全性出发,论述了浅埋偏压隧道的设计与施工情况。以右线出洞口为例,采用三维快速拉格朗日差分法(FLAC^(3D)),对其施工开挖过程及支护进行了模拟。通过对开挖支护后围岩的应力场、位移场及塑性区特征的分析,得出了一些建设性的结论,对工程的施工具有指导意义。

Longtan tunnel,a key part of HU-Rong Expressway engineering including many geological problems such as shallow cover,unsymmetrical pressure,water rush,mud rush and rock burst,is a representative of long and broad expressway tunnel under complex geological conditions.It is very difficult for engineer to build tunnels with shallow cover and unsymmetrical loading.The design and construction of Longtan Tunnel are described from safety point of excavation and support.FLAC^(3D) is used to simulate the excavation and supporting process of the exit section of Longtan Tunnel under the condition of shallow cover and uneven pressure. Some conclusions are drawn through analyzing the characters of stress and displacement fields and plastic zone of surrounding rock after excavation.It will be useful for the project construction.