隧道开挖诱发滑坡与衬砌开裂处治与分析

Treatment and Analysis of Landslide and Lining Cracking Induced by Tunnel Excavation

山区隧道的勘察设计通常都会规避穿越大型滑坡,但山区隧道洞口段不可避免穿越斜坡。隧道工程建设中经常出现因隧道开挖诱发古滑坡体和斜边坡变形滑动,从而导致隧道坍塌和衬砌开裂。以寒山口隧道为例,探讨了隧道施工诱发边坡滑动和衬砌开裂的机理,评价了加固措施的有效性,并根据衬砌裂缝的分布特征和宽度随时间变化规律,再结合衬砌整体的变形特征,总结得到了2种衬砌开裂机理。其中,第1种类型为衬砌内张拉裂缝,对应着隧道深埋侧拱脚裂缝形成机理,裂缝处于张开状态,宽度较大,且其宽度随时间的变化较为明显;第2种类型为衬砌内压缩裂缝,对应着隧道浅埋侧拱肩裂缝的形成机理,裂缝一般处于闭合状态,宽度较小,且宽度随时间的变化较小。

The survey and design of tunnels in mountainous areas usually avoid tunnels crossing large landslides,but the portal section of mountain tunnel inevitably crosses the slope.During tunnel construction,deformation and sliding of ancient landslide and slope often occur by tunnel excavation,which cause collapse and lining cracking.Taken Hanshankou tunnel as a project case,the mechanism of slope sliding and lining cracking induced by tunnel construction is discussed and the effectiveness of reinforcement measures is evaluated.According to the distribution characteristics of lining cracks and the variation law of width with time,combined with the deformation characteristics of the whole lining,two types of lining cracking mechanisms are summarized.The first type is the tension crack in the lining,which corresponds to the formation mechanism of the cracks in the deep buried side arch foot of the tunnel.This kind of crack is in an open state with general larger width.And the width changes obviously with time;The second type is the compression crack in the lining,which corresponds to the formation mechanism of the shallow side arch shoulder crack of the tunnel.This kind of crack is generally in a closed state with smaller width and smaller change of width with time.