高铁拱塔斜拉桥跨运营铁路主梁顶推控制分析

Analysis of Incremental Launching Control of Main Girder of Arch-Shaped Pylon for High-Speed Railway Cable-Stayed Bridge across Operating Railway

顶推施工能够有效降低跨运营铁路主梁施工对既有线路的影响,而顶推施工方案选择及主梁线形控制对于主梁能否顺利合龙及成桥线形有直接影响。以常益长高速铁路跨石长铁路拱塔斜拉桥的主梁顶推施工为依托,建立全桥有限元模型,模拟两种顶推施工方案;通过试算确定临时扣索及拱索索力,以控制顶推过程中主梁的线形变化及受力,确保主梁的安全精准合龙。结果表明,扣索方案,小、大里程侧转角分别为0.0003、0.0001 rad,两侧主梁竖向位移均为-30 mm,扣索索力最大2860 kN,钢梁应力介于-34.09~31.76 MPa之间,扣塔应力介于-130.84~58.31 MPa之间;扣索+拱索方案,小、大里程侧转角分别为0.0003、0.0001 rad,两侧主梁竖向位移均为-31 mm,扣索索力最大2580 kN,拱索160 kN,钢梁应力介于-34.40~32.81 MPa之间,扣塔应力介于-124.64~55.21 MPa之间;两种方案下合龙线形及受力均在合理范围内。不同合龙方案成桥钢梁应力差值均在1.0 MPa以内,成桥位移差值在1.0 mm以内,两者差异极小。为施工简便,优先推荐张拉扣索方案。

Incremental launching construction can effectively reduce the impact on the existing railway during the construction of the main girder across the operating railway,and the construction methods selection and alignment control of the main girder directly affect the smooth closure of the main girder and the alignment of the bridge.Based on the incremental construction of the main girder of the arch-shaped pylon cable-stayed bridge of Changsha-Yiyang-Changde High-speed Railway over Shimen-Changsha Railway,a full bridge finite element model is established to simulate two construction schemes.The forces of temporary buckle cable and arch cable are determined through trial calculations to control the linear change and stress of the main girder during the process of launching and ensure the safe and accurate closure of the main girder.The results show that under the buckle cable scheme,the rotation angle of small and large mileage sides are 0.0003 rad and 0.0001 rad respectively,the vertical displacement of main beams on both sides is-30 mm,the maximum cable force is 2860 kN,the stresses of steel beam are between-34.09 and-31.76 MPa,and the stresses of buckle tower are between-130.84 and-58.31 MPa.Under the scheme of buckle cable and arch cable,the rotation angle of small and large mileage sides are 0.0003 rad and 0.0001 rad respectively,the vertical displacement of main beams on both sides is-31 mm,the maximum cable force is 2580 kN,the arch cable force is 160 kN,the stresses of steel girder are-34.40~32.81 MPa,and the stress of buckle tower are between-124.64 and-55.21 MPa.Under the two schemes,the closure alignment and force are in a reasonable range.Under different closure schemes,the stress differences of the completed bridge are within 1.0 MPa,and the displacement differences of the completed bridge are within 1.0 mm,and the difference between the two schemes is extremely small.The buckle cable scheme is recommended for construction convenience.