隧道洞口段危岩落石风险评估

Rockfall Risk Assessment for a Tunnel Portal Section

由于线路的走向及场地的限制,许多隧道进出口的边、仰坡高陡、地质条件恶劣,在雨水及地震等自然灾害的作用下,会形成危岩、落石、崩塌等,对隧道洞口段及相邻的桥梁、线路造成危害,危及行车安全。文章参考有关道路边坡落石风险评估技术,从系统/问题的定义入手,将隧道工程系统分为洞口段工程和洞身段工程等子系统,以使问题分析更加明确;提出采用初步定性评估和细部定量评估的隧道洞口段危岩落石风险评估方法,并应用于在建的兰渝线隧道洞口段工程;应用Rockfall软件,进行了范家坪隧道出口仰坡危岩落石运动轨迹的预测,结果表明原设计的明洞长度不能满足对防治山上危岩落石的要求。

Rockfalls and landslides often endanger the safety of portal sections of tunnels.Referring to the risk assessment technology of highway slope rockfall,the system of a tunnel is divided into two subsystems： portal section and body of the tunnel.The approach of primary qualitative and detailed quantitative assessments was adopted;the method of the rockfall risk assessment for the portal section was applied to Fanjiaping tunnel on Lanzhou-Chongqing railway under construction.The grey forecast for the falling stone＇s trajectory of the tunnel entrance front slope was carried through by using software Rockfall.Results indicated that the original design length of open-cut tunnel could not meet the needs for the prevention and treatment of rockfall.