挤压性围岩大跨隧道预应力锚索施作时机研究

Research of the Reasonable Installation Time of the Pre-stressed Anchor Cables for Large-span Tunnels in Squeezing Rocks

依托兰渝铁路新城子隧道工程,文章采用数值模拟分析结合工程实际的方法,开展挤压性围岩大跨隧道双侧壁导坑法施工中预应力锚索的作用机制和施作时机研究。数值模拟研究表明,预应力锚索滞后掌子面一段距离施作,能有效控制变形又不影响应力释放;结合现场预应力锚索的施工经验,总结出了预应力锚索的钻孔时机、张拉方式及单次张拉建议值。

In view of the Xinchengzi tunnel on Lanzhou-Chongqing railway,the action mechanism and installation time of pre-stressed anchor cables in squeezing rock tunnel with double side heading construction method are discussed and researched by the numerical simulation combined with practical experience.Numerical comparative analysis shows that,it is an effective way to actively control the deformations and does not affect the stress release when pre-stressed anchor cables are installed with lagging a certain distance from the face in squeezing rock tunnel with double side heading construction method.Meanwhile,according to the construction experience,the drilling time,tensioning method and first tensioning value for pre-stressed anchor cable are recommended.