重庆铁路转体桥施工力学特性分析及监控

Analysis of Mechanical Characteristics and Monitoring of Chongqing Railway Rotating Bridge

以重庆铁路枢纽东环线珞璜南右线特大桥连续梁跨越既有渝贵线铁路工程为依托,研究了转体桥施工力学特性及监控技术。采用Midas civil软件建立桥梁模型,研究转体桥关键工况的力学特性,对比分析了桥梁变形、内力的数值模拟值与现场实测值。结果表明:危险工况中箱梁截面应力最大发生在跨中,其值为12.36 MPa,位移最大发生在8#梁段与9#梁段交界面,其值为26.34 mm。支座及跨中两个位置是关键工况中危险受力处,悬臂根部截面应选为应力监测截面。线形监测表明在转体施工过程中,小里程、大里程侧梁顶标高数值模拟值与实测值差值最大分别为17 mm、19 mm;转体完成拆除支架后,主梁线形变化较大,小里程、大里程侧变化最大分别为16 mm、20 mm。悬臂梁根部应力监测表明,顶板应力值始终大于底板应力值,最大压应力发生在顶板处,其值为8.14 MPa,小于C55混凝土抗压强度标准值,顶板、底板处应力数值模拟值与实测值差值最大分别为0.92 MPa、0.81 MPa。以上均满足设计要求,保证了转体施工安全,为同类型施工提供了借鉴经验。

Based on the project of the continuous beam crossing over the existing chongqing-guizhou railway of LuoHuang-South Right Line Bridge in the Chongqing Railway Junction East Ring Line,the construction mechanical characteristics and monitoring technology of rotating bridge are studied.Midas civil software is used to build the bridge model,and the mechanical characteristics of the key working conditions of the swivel bridge are studied.The numerical simulation values of the bridge deformation and internal force are compared with the field measured values.The results show that the maximum stress of box girder section occurs in the middle of span and its value is 12.36 MPa.The maximum displacement occurs at the interface of 8#beam section and 9#beam section,and its value is 26.34 mm.Bridge bearing and midspan are the dangerous stress positions in key working conditions,and the cantilever root section should be selected as the stress monitoring section.The alignment monitoring shows that the maximum difference between the numerical simulation value and the measured value of the top elevation of the side beam of small mileage and large mileage is 17 mm and 19 mm respectively in the process of swivel construction;after the swivel is completed to remove the support,the alignment of the main beam changes greatly,and the maximum changes of the side of small mileage and large mileage are 16 mm and 20 mm respectively.The monitoring of the stress of the cantilever root section shows that the stress value of the top plate is always greater than that of the bottom plate,and the maximum compressive stress occurs at the top plate,which is 8.14 MPa and less than the standard value of C55 concrete compressive strength.The maximum difference between the numerical simulation value and the measured value of the stress at the top plate and the bottom plate is0.92 MPa and 0.81 MPa respectively.All of the above meet the design requirements,ensuring the safety of rotating construction,and provide referential experience for the same type of construction.