深埋软岩公路隧道大变形段双层支护方案研究

RESEARCH ON DOUBLE-LAYER SUPPORT SCHEME IN LARGE DEFORMATION SECTION OF DEEP-BURIED SOFT ROCK HIGHWAY TUNNEL

根据云南省云临高速公路大亮山隧道穿越复杂地质条件时出现的初期支护开裂、仰拱隆起等灾害,单层初期支护无法抵抗围岩压力,采用双层初期支护进行优化设计。利用有限差分数值模拟软件对单层初期支护与双层初期支护开挖后围岩与支护结构力学响应进行对比,并与现场监测数据对比分析。研究结果表明:单层初期支护拱顶沉降、仰拱隆起、二次衬砌内力、塑性区半径均大于双层初期支护,采用双层初期支护可以保障隧道安全掘进;针对隧道拱顶沉降与仰拱隆起变形曲线,建议采用扩大拱脚、尽早施作仰拱、增设锁脚锚杆等措施控制隧道的变形、开裂等灾害。

In this paper,according to the disasters such as initial branch cracking and inverted arch uplift occurred when the Daliangshan Tunnel of Yunlin Expressway in Yunnan Province passes through complex geological conditions,the single-layer initial support cannot resist the surrounding rock pressure,and the double-layer initial support is used to optimize the design.The finite difference numerical simulation software was used to compare the mechanical responses of the surrounding rock and the supporting structure after the excavation of the single-layer initial support and the double-layer initial support,and compared with the field monitoring data.The research results show that the single-layer primary support vault settlement,inverted arch uplift,lining internal force,and plastic zone radius are all larger than those of the double-layer primary support.For the deformation curve of the arch uplift,it is recommended to take measures such as enlarging the arch feet,applying the inverted arch as soon as possible,and adding locking anchors to control the deformation and cracking of the tunnel.