卵石流塑地层盾构下穿铁路框架桥加固技术与变形控制研究

Study on Reinforcement Technology and Deformation Control of Shield Tunnel in Pebble Flow Plastic Stratum under Railway Frame Bridge

针对卵石流塑地层盾构隧道下穿施工诱发地表及其地表建(构)物变形过大等问题,以长沙轨道交通3号线盾构隧道下穿京广铁路框架桥为背景,提出"袖阀管注浆加固"与"深层二次注浆"技术,并通过数值计算分析了盾构掘进过程对京广铁路框架桥的影响,探讨地层加固前后盾构下穿地表变形情况以及铁路框架桥的稳定性。研究结果表明:未采取地层加固措施盾构下穿京广铁路框架桥围岩及地表变形较大,地表沉降量高达35.13 mm,组成框架桥的9个箱涵之间不均匀变形较大,最大沉降量发生在先行施工隧道上部,轨道变形最大值为6.18 mm,远大于规范要求,采取地层加固措施后,地表沉降得到有效控制,框架桥不均匀沉降相对于未加固工况,差异沉降减小约48.1%,保证了铁路运营安全。

The shield tunnel in pebble flow-plastic stratum passing under railway frame bridge leads likely to the excessive deformation of the surface and surface constructions（structures）. With referenced to the Changsha rail transit line 3 shield tunnel passing under the Beijing-Guangzhou railway frame bridge,this paper puts forward the ＂sleeve valve grouting reinforcement＂and ＂deep secondary grouting＂technologies,and through numerical calculation analyzes the influence of shield tunneling on the bridge,the stability of the railway frame bridge before and after the formation reinforcement. Research results show that the surrounding rock and surface deformation caused by the shield tunnel passing under the Beijing-Guangzhou railway frame bridge is large,the surface subsidence reaches as high as 35. 13 mm without reinforcement;the non-uniform deformation of the nine box culverts constituting the frame bridge is large,and the maximum settlement occurs in the upper part of the first construction tunnel. The maximum track deformation is 6. 18 mm,which is much higher than the specification. Ground subsidence is effectively controlled by means of reinforcement measures and the uneven settlement of the frame bridge is lowered by some 48. 1% with respect to that under non-reinforcement condition to ensure the safety of railway operations.