富水卵石层桩底小净距盾构下穿京台高速公路桥梁变形控制措施

以济南市轨道交通R1线王府庄站~大杨庄站区间盾构隧道下穿京台高速公路桥梁为工程依托,采用MIDAS-GTS有限元软件建立三维计算模型对比分析有无注浆两种工况下桥墩变形特征,计算结果表明：无注浆加固条件下,桥墩竖向沉降最大值达10.24mm,接近变形控制值10.0mm；采用袖阀管注浆加固条件下,桥墩竖向沉降最大值为6.35mm,加固效果对保护桥梁变形效果明显。施工过程中通过控制盾构掘进参数、同步注浆、补强注浆、渣土改良技术等施工精细化技术措施来减小盾构施工对桥梁扰动；针对桥梁沉降达到预警值、控制值分阶段采取洞内径向注浆、应急支顶措施,确保桥梁结构安全。监测结果显示,盾构整个穿越过程中,桥墩最大沉降值为3.11mm,表明袖阀管注浆加固对控制桥梁变形起到很好地效果。

Study on Deformation Control Measures of Bridges with Small Clear Spacing in Pile Bottom Crossing Beijing-Taibei Expressway in Water-rich Pebble Layer

Relying on the Beijing-Taibei Expressway Bridge under the shield tunnel between Wangfuzhuang Station and Dayangzhuang Station of Jinan Rail Transit Line R1. Using MIDAS-GTS finite element software to establish a three-dimensional calculation model to compare and analyze the deformation characteristics of the pier under the two conditions of grouting. The calculation results show that without grouting reinforcement the maximum vertical settlement of the pier is 10.24mm. which is close to the deformation control value of 10.0mm. The maximum vertical settlement of the pier is 6.35mm under the condition of sleeve valve tube grouting reinforcement and the reinforcement effect is obvious to protect the deformation of the bridge. During the construction process, through the control of shield tunneling parameters, synchronous grouting, reinforced grouting, and slag soil improvement technology, the construction of refined technical measures to reduce the disturbance of the shield construction on the bridge. The monitoring results show that the maximum settlement value of the bridge pier during the entire passage of the shield is 3.11mm, indicating that the sleeve valve tube grouting reinforcement has a good effect on controlling the deformation of the bridge.