高地应力软岩隧道围岩大变形控制关键技术研究

Study on key technologies for controlling large deformation of soft rock tunnel under high ground stress

高地应力软弱围岩隧道施工易发生软岩大变形不良地质灾害,进一步引发掌子面失稳塌方、初支结构破坏、钢拱架弯折、初支结构侵限等不良现象,严重影响施工安全,阻碍工期。依托九绵高速白马隧道工程,采用现场监测的研究手段,从围岩特性、施工工法、循环步距等方面系统分析白马隧道产生大变形的根本原因,并从围岩变形机理出发,提出了一套综合施工工法、支护措施等方面的软岩大变形防治方案,解决了高地应力软岩大变形隧道初期支护受围岩应力挤压收敛变形的难题,实现了隧道初期支护无开裂、扭曲、折断、侵限的目的,可为类似工程提供一定参考。

The construction of tunnels with high stress and weak surrounding rock is prone to geological disasters such as large deformation of soft rock,which can further cause instability and collapse of the tunnel face,damage to the initial support structure,bending of steel arches,and intrusion of the initial support structure,seriously affecting construction safety and hindering the construction period.This article relies on the Baima Tunnel project of the Jiumian Expressway and adopts on-site monitoring research methods to systematically analyze the fundamental reasons for the large deformation of the Baima Tunnel from the aspects of surrounding rock characteristics,construction methods,and cycle step distance.Starting from the deformation mechanism of the surrounding rock,a comprehensive soft rock large deformation prevention and control plan is proposed in terms of construction methods,support measures,and other aspects,Solved the problem of convergence deformation of initial support in high stress soft rock large deformation tunnels under surrounding rock stress compression,and achieved the goal of no cracking,distortion,fracture,and intrusion in initial support of tunnels,which can provide certain reference value for similar projects.