盾构下穿铁路桥涵变形规律及控制技术研究

Rules and control technology of deformation caused by shield tunnel under-passing the railway bridge culvert

以济南轨道交通R1线玉符河站-王府庄站区间盾构隧道下穿京沪铁路框架桥涵为背景,采用flac^3D软件进行数值模拟,分析下穿施工中桥涵结构应力变形和铁路轨道变形特征.结果表明：下穿过程中桥涵最大压应力位于盾构左线上方立柱,其值为5.06MPa,最大拉应力位于桥涵右恻顶部,其值为1.00MPa;穿越过程桥涵最大沉降值达到5.81mm,均满足结构应力、变形控制标准;由桥涵上方各轨道的最终变形曲线与左、右线拱顶上方轨道的变形时程曲线得出靠近施工恻轨道先于其他轨道产生沉降,最终沉降值随开挖方向依次增大至3.76mm.结合分析结果提出盾构下穿铁路桥涵施工控制技术及监测控制方案,确定了盾构下穿施工20m范围为重点监测区,并提出适用于济南轨道交通建设的沉降控制标准.

In the engineering background of the Jinan rail transit line R1 line Yufu River Station -Wangfu - zhuang station shield tunnel under - passing the Beijing - Shanghai railway frame bridge. With the help of FLAC^3D,the deformation and stress of the bridge structure is simulated numerically and the characteristics of railway track deformation are analyzed. The calculation results show that the maximum compressive stress of bridge is 5.06 MPa in the position of the column above the left line of the shield at the process of under-passing bridge, and the maximum tensile stress of bridge is 1.00 MPa at the top of the bridge culvert right side; sedimen-tation value of the bridge culvert through the process reached 5.81 mm. These results all meet the stress and de-formation control standards. Based on the final deformation curves of track structure above bridge culvert and de-formation time history curves of track at the top of the left and right lines. It is concluded that the rail track close to construction side get settlement before the other tracks, the final settlement value increases with the excavation direction to 3.76 mm. Combined with the results of the analysis,construction control technologies and monitoring and control schemes are proposed for the shield tunnel under-passing the railway bridge culvert. The scope of 20 m is determined as the key monitoring area and settlement control standards for the construction of Jinan rail tran-sit are presented.