铁路隧道二次衬砌施工冷缝成因及对策

Causes and Countermeasures of Cold Joints in Secondary Lining Construction of Railway Tunnel

针对隧道二次衬砌冷缝掉块问题,运用数值模拟方法,对比分析素混凝土和钢筋混凝土二次衬砌存在冷缝条件下结构受力与变形特征;模拟不同位置冷缝对二次衬砌结构安全性的影响。结果表明:集中降雨导致水头压力突增,无法通过冷缝均匀传递,局部区域沿冷缝发生错动变形与整体弯折破坏,致使二次衬砌掉块;在同种工况下钢筋混凝土可有效提升二次衬砌承载能力;拱腰处冷缝较其他部位对二次衬砌整体结构影响更大。通过总结现场经验及数值模拟分析结果,提出了控制冷缝质量事故及排查整治的建议。

Aiming at the problem of cold joint drop of tunnel secondary lining,the structural stress and deformation characteristics of plain concrete and reinforced concrete secondary lining with cold joint were compared and analyzed by numerical simulation method. The influence of cold joint conditions at different positions on the safety of secondary lining structure was simulated. The results show that the sudden increase of water head pressure caused by concentrated rainfall cannot be uniformly transmitted through the cold joint,resulting in dislocation deformation and overall bending failure in local areas along the cold joint,resulting in the secondary lining falling;reinforced concrete can effectively improve the bearing capacity of secondary lining under the same conditions;the cold joint at the arch waist has the greatest influence on the overall structure of the secondary lining. Through summarizing the field experience and the conclusion of numerical simulation analysis,the suggestions for controlling the quality accident of cold joint and investigating and repairing were put forward.