浅埋大跨度隧道大变形演化特征与防治方法

Characteristics of large deformation and prevention methods for shallow buried large span tunnels

为解决浅埋大跨度隧道在施工中常出现的初期支护大变形及冒顶病害等问题,本研究依托广西壮族自治区百色市某隧道工程,分析了该隧道的大变形及冒顶灾害特征。基于PFC离散元软件,分析了隧道失稳演化规律,提出了隧道初期支护大变形处治技术。研究结果表明:浅埋大跨度隧道施工时,容易受围岩条件及支护强度等影响,从而引起围岩大变形或塌方灾害。采用地表注浆加固或临时仰拱与洞内反压等技术处理后,围岩变形得到了有效控制。现场施工时,应通过建立管理体系,加强人员培训,设置安全通道,安排安全人员,强化安全意识,建立评估与预警机制等保障措施,降低安全风险。该研究成果可为浅埋大跨度隧道施工灾害防治提供参考。

In order to solve diseases such as large deformation of initial support or roof caving that occurs frequently in the construction of shallow-buried large-span tunnels,the characteristics of large deformation and roof caving disaster were analyzed based on the tunnel in Baise City Guangxi Province.The PFC discrete element software was used to analyze the evolution of instability.The treatment technology of large deformation of tunnel primary support was put forward.The results show that,during the construction of shallow-buried large-span tunnel,it is easy to be affected by factors such as surrounding rock conditions and support strength,resulting in large deformation or collapse of surrounding rock.The deformation of surrounding rock can be effectively controlled by means of surface grouting reinforcement,temporary inverted arch and back pressure in tunnel.Security risks can be reduced by establishing management system,strengthening personnel training,setting up safety channels,arranging safety personnel,strengthening safety awareness,and establishing evaluation and early warning mechanisms.The research results can provide reference for the prevention and control of construction disasters in shallow buried large-span tunnel.