复杂地质隧道施工的沉降变形分析

针对黄土隧道围岩强度低、自承载力弱、开挖变形大的问题,基于数值模拟法对黄土隧道施工过程模拟仿真,得到隧道围岩开挖溶洞的位移变形特征和应力变化,并给出相应的隧道变形沉降控制措施。研究结果表明:隧道开挖过程中,掌子面上部围岩形成一个U形的整体沉降区,由隧道表面延伸到拱脚处,边界接近垂直。隧道开挖对围岩影响集中在隧道中线35 m范围,掌子面前方20 m内,其中在隧道中线20 m,掌子面前方6 m沉降值达到总沉降的24%~45%,沉降集中在掌子面至初支护封闭阶段。实际工程中,可通过加强拱脚强度、提高初期支护和超前支护、减少封闭距离来有效控制围岩沉降变形。

Analysis of Settlement Deformation of Complex Geological Tunnel Construction

Aiming at the problems of low strength,weak self-bearing capacity and large excavation deformation of surrounding rock in loess tunnel.Based on the numerical simulation method,the construction technology of the arc guide pit method of loess tunnel is simulated,and the displacement deformation characteristics and stress change of the surrounding rock excavation cave of loess tunnel are obtained,and the corresponding control measures of tunnel deformation and settlement are given.During tunnel excavation,the surrounding rock of the upper face of the tunnel forms a U shape integral settlement area,extending from the tunnel surface to the arch foot,and the boundary is close to vertical.The influence of tunnel excavation on surrounding rock is mainly concentrated in the range of 20 in front of the tunnel m,35 m transversely from the middle line of the tunnel,among which in front of the tunnel The settlement effect of square 6 m,20 m from the middle line of the tunnel is significant,which can reach 24%~45%of the final settlement.The settlement is mainly concentrated in the closed stage of palm face to initial support.In practical engineering,the settlement deformation of surrounding rock can be effectively controlled by strengthening the strength of arch foot,increasing the initial support and advance support,and reducing the closed distance.