浅埋双侧偏压小净距隧道开挖稳定性分析

摘要

In order to study deformation of wall rock and stress distribution rules of support structures after excavation of shallow buried double -side unsymmetrical loading small clear distance tunnels,this paper studies and analyzes distribution of plastic zones of wall rock,distribution of vertical and horizontal displacements after excavation and support of left and right portals of small clear distance tunnels as well as bending moment,axial and shear stress of initial supporting structures by means of numerical analysis method.The results of study show that plastic zones mainly distribute at arch feet on both sides of left and right portals of tunnels after excavation of shallow buried unsymmetrical loading small clear distance tunnels,the vertical displacement at arc top is maximal,and horizontal displacement at haunch is maximal;both the bending moment and shear stress of initial supporting structures at side walls are big, and the axial stress at the haunch is maximal.The paper recommends that support of side walls and arch feet of tunnels and monitoring for empty deformation inside the tunnels should be strengthened during design and construction of such type tunnels.%为了研究浅埋双侧偏压小净距隧道开挖后围岩变形及支护结构受力分布规律，以某高速公路隧道为依托，采用数值分析方法对小净距隧道左右洞开挖支护完毕后的围岩塑性区分布、竖直和水平位移分布，以及初期支护结构的弯矩、轴力和剪力进行研究和分析。研究结果表明：浅埋偏压小净距隧道开挖后塑性区主要分布在隧道左右洞的两侧拱脚处，拱顶处竖向位移最大，拱腰处水平位移最大；初期支护结构在边墙处的弯矩和剪力均较大，轴力在拱腰处最大。建议该类型隧道设计与施工时需加强对隧道边墙及拱脚处的支护，并加强隧道内空变形监测。