超宽3塔钢箱梁斜拉桥实时监测与反馈分析研究

Study on Real-time Monitoring and Feedback Analysis of an Ultra-wide Three-pylon Steel Box Girder Cable-stayed Bridge

摘要:

以某超宽3塔钢箱梁斜拉桥为工程背景，基于现场实时监测结果，研究了超宽3塔钢箱梁斜拉桥施工监控技术。结果表明：在圆形混合塔柱施工过程中，结构几何非线性影响较明显，易导致斜拉索张索阶段主塔实测纵向偏位值大于理论预测值；两合龙口预留宽度较宽（最宽达10 m），导致合龙前合龙口两端主梁高差控制极为困难，需结合斜拉索调索方案实施。从现场情况来看，斜拉索调索完成后，主梁合龙口两端高程控制较好，理论值与实测值偏差均在±1.5 cm以内。成桥阶段主梁线形状态良好，实测高程与成桥目标高程基本吻合，误差为-0.6~5.8 cm；施工阶段主梁及主塔应力状态良好，实测值与理论值较接近，主塔混凝土塔根最大应力在3.3 MPa以内，钢塔最大应力在100 MPa以内，主梁底板最大应力在80 MPa以内。全桥各斜拉索索力状况良好，实测索力与目标索力相对差值基本在±5%以内。

Abstract:

Taking an ultra-wide three-pylon steel box girder cable-stayed bridge as the engineering background, based on the field real-time monitoring results, the construction monitoring technology of this bridge is studied. The result shows that the influence of structural geometric nonlinearity is relatively obvious during the construction process of circular mixed pylon columns, which is prone to cause the measured longitudinal deviation value of the main pylon during the tensioning stage of the stayed cables to be greater than the theoretical predicted value. Due to the wide reserved width (up to 10 m), it is extremely difficult to control the height difference of the main girder at both ends of the closure before closure completion, which needs to be implemented in combination with the stayed cable adjustment scheme. The field observations show that after the cable adjustments, the elevation at the closure ends of the main girder is well-controlled. The deviation between theoretical and measured values is within ±1.5 cm. During the stage of bridge completion, the linear condition of the main girder is good. The measured elevation is basically in line with the target elevation for bridge completion, and an error is from -0.6 cm to 5.8 cm. Additionally, during the construction, the stress states of the main girder and main pylon are good, and the measured values are close to the theoretical values. The maximum stress at the concrete pylon root of the main girder is within 3.3 MPa, the maximum stress in the steel pylon is within 100 MPa, and the maximum stress in the bottom plate of the main girder is within 80 MPa. Furthermore, the cable force of all the stayed cables on the entire bridge is in good condition, and the relative difference between the measured cable force and the target cable force is basically within ±5%.