3种隧道洞口落石防护方案对比分析

为解决既有隧道洞口落石防护问题,比较了钢桁架棚洞、柔性棚洞以及波纹钢板棚洞3种落石防护结构的优缺点,并采用有限元软件对其可靠性进行数值模拟。研究结果表明:3种防护结构均能对能级为100 kJ的落石进行有效拦截;钢桁架棚洞为刚性结构,不利于落石的缓冲及能量吸收,会发生局部变形损伤,适用于洞口坡面陡峭、桥面与地面高差不大、围岩条件较好地段;柔性棚洞以柔克刚能充分吸收落石的冲击能量,适用于洞口场地施工条件差的隧道以及既有工程改造项目;波纹钢板棚洞施工速度快、强度高,更适用于洞口抢修工程。

Comparative Analysis of Three Kinds of Protection Schemes for Rockfall at Tunnel Portal

In order to solve the problem of rockfall protection of existing tunnel portal,the advantages and disadvantages of three kinds of rockfall protection structures including steel truss shed,flexible shed and corrugated steel sheet shed were compared,and the reliabilities of them were simulated by finite element software.The results show that all the three protection structures can effectively intercept the rockfall with energy level of 100 kJ.The steel truss shed is a rigid structure,which is not conducive to the buffering and energy absorption of rockfall,and will cause local deformation and damage.The steel truss shed is suitable for sections with steep slope at the portal,small height difference between the bridge deck and the ground,and good surrounding rock conditions.The flexible shed can fully absorb the impact energy of rockfall with the flexibility to overcome the rigidity,which is suitable for tunnels with poor construction conditions at the portal and existing engineering reconstruction projects.The corrugated steel sheet shed has the advantages of fast construction speed and high strength,which is more suitable for the emergency repair of the tunnel portal.