某隧道出口边坡加固措施费效比研究

Cost-effectiveness Study of Slope Reinforcement Methods at Tunnel Portals

以某公路隧道出口边坡为研究对象,利用反分析方法和工程类比法确定了边坡坡体当前的强度参数,分别计算了主动加固和被动加固对其稳定性和滑动范围造成的影响,结果表明,主动加固坡体强度参数降低不大、变形范围有限,坡体稳定,被动加固使得坡体扰动范围增加、坡体强度降低较大,坡体不稳,且加固费效比低。最终建议,隧道进口边坡采取桩板墙主动加固,出口边坡对原设计的预应力锚索做了补强处理,经运行边坡稳定状态良好。

The stability of slopes at portals is often critical to a successful tunnel construction. This paper presents a slope sta- bility analysis on the portals of a highway tunnel. The strength parameters are estimated throughout back analysis as well as engineering analog. The impacts of active and passive strengthening methods on the slope stability and its sliding influence zone are evaluated. The comparative study results indicate that, if the active strengthening methods are used, strength reduction and deformation zone in the sliding body are limited. Larger deformation and strength reduction can be found in the potential sliding body if the passive strengthening methods are utilized. The cost and effectiveness ratio is also low for the passive strengthening methods. The final design used active strengthening methods at both entrance and exit portals. The sheet pile wall was in- stalled at the tunnel entrance and the prestressed ground anchors were installed at the exit portal. The tunnel operation period demonstrates that the slopes are stable and satisfactory.