城市大跨下承式单承载面系杆拱桥吊杆更换施工监控技术

Construction Monitoring Technology of Suspender Replacement of Urban Long-span through Single-bearing Surface Bowstring Arch Bridge

摘要:

以宁波市大跨下承式单承载面系杆拱桥——琴桥为工程背景，针对吊杆更换施工过程中存在的问题，采用仿真分析与现场监测相结合的方法，通过对比分析理论计算值与实测数据，确定了吊杆更换方案、成桥目标索力以及吊杆的下料长度，分析了吊杆更换过程中的桥梁结构响应，明确了现场监测预警值指标。结果表明：与单根吊杆更换相比，同时更换一对吊杆的结构响应基本上成倍增加，建议严格按照设计要求，对吊杆进行逐根更换；与吊杆更换前的桥梁结构状态相比，吊杆更换过程中及吊杆更换施工完成后的主梁和主拱的线形、应力及吊杆索力变化均控制在合理范围内，满足相关控制精度要求。

Abstract:

Taking a long-span through single-bearing surface bowstring arch bridge - Qin Bridge in Ningbo as the engineering background, aiming at the problems existing in the construction process of suspender replacement, the method combining the simulation analysis and field monitoring is used to confirm the suspender replacement scheme, target cable force of finished bridge and suspender length by comparing and analyzing the theoretical calculating value and the measured data. The response of bridge structure in the process of derrick replacement is analyzed, and the index of field monitoring and warning value is defined. The results show that compared with the replacement of a single suspender, the structural response of replacing a pair of booms at the same time is basically doubled. It is recommended to replace the suspender one by one in strict accordance with the design requirements. Compared with the bridge structural state before the suspender is replaced, the linear shape, stress and cable force changes of the main girder and main arch during and after the replacement of the suspender are controlled within a reasonable range, and meet the relevant control accuracy requirements.