永–临支护型鸟笼锚索结构组成及其在软岩隧道中的工艺性试验

Structural Composition of Permanently-Temporarily Supported Birdcage Anchor Cable and Its Processability Test in Soft Rock Tunnel

摘要: 为在软岩隧道中实现及时主动支护，研制了“及时(树脂端锚) + 永久(水泥浆全长锚固)”快速预应力鸟笼锚索系统，并依托木寨岭公路隧道，对该鸟笼锚索的具体施工工艺、锚固及支护效果等进行了现场试验。得到结论如下：鸟笼锚索系统的关键施工工序为搅拌锚固、张拉锁定及后注浆，涉及搅拌时间和静置时间两个关键性参数；在软岩大变形段开展的现场锚固拉拔试验表明，鸟笼锚索系统具备极佳的主动支护能力，树脂搅拌完成后15 min即可进行预应力施加，且1 m树脂锚固长度的拉拔力能够达到400 kN以上；依托该锚索开展的现场试验段变形实现了最大变形量由529 mm到229 mm的转变，围岩位移控制效果显著。

Abstract: In order to realize timely active support in soft rock tunnel, the “timely (resin end anchor) + permanent (cement slurry full-length anchorage)” fast prestressed birdcage anchor system was developed. Relying on the Muzhailing Highway Tunnel, field tests were conducted on the specific construction process, anchorage and support effect of this birdcage anchor cable. The following conclusions were obtained: the key construction processes of the birdcage anchor system are mixing and anchoring, tensioning and locking, and post-grouting, which involve two key parameters: mixing time and resting time. On-site anchor pull-out tests conducted in a large deformation section of soft rock show that the birdcage anchor system has excellent active support capability, the pre-stress can be applied 15 minutes after the resin mixing is completed, and the pull-out force of 1 m resin anchorage length can reach over 400 kN. The deformation of the field test section based on this anchor cable has achieved the change of the maximum deformation from 529 mm to 229 mm, and the effect of surrounding rock displacement control is remarkable.